Fix required by suitesparse to build Mongoose

The CMakeLists.txt of Mongoose assumes that SuiteSparse_config has been
installed into the suitesparse source directory, which is not the case
for us, as we are building suitesparse out-of-tree.

SuiteSparse_config can instead be found in the ${CMAKE_INSTALL_PREFIX}
directory.

diff --git a/Mongoose/CMakeLists.txt b/Mongoose/CMakeLists.txt
index 7e134ab..76fa9e2 100644
--- a/Mongoose/CMakeLists.txt
+++ b/Mongoose/CMakeLists.txt
@@ -148,10 +148,10 @@ set(CMAKE_CXX_STANDARD 11)
 #set(CMAKE_CXX_STANDARD_REQUIRED ON)

 # determine which SuiteSparse_config to use
-if (EXISTS ${PROJECT_SOURCE_DIR}/../SuiteSparse_config)
-    message(STATUS "External ../SuiteSparse_config" ${BoldBlue} " found" ${ColourReset} ".")
+if (EXISTS ${CMAKE_INSTALL_PREFIX})
+    message(STATUS "External SuiteSparse_config" ${BoldBlue} " found" ${ColourReset} ".")
     set ( SUITESPARSE_CONFIG_DIR ${PROJECT_SOURCE_DIR}/../SuiteSparse_config )
-    link_directories ( ${PROJECT_SOURCE_DIR}/../lib )
+    link_directories ( ${CMAKE_INSTALL_PREFIX}/lib )
     message ( STATUS "Note: ../SuiteSparse_config must be compiled before compiling Mongoose" )
     set ( SUITESPARSE_CONFIG_LIBRARY suitesparseconfig )
 else ()
='/guix/tree/gnu/tests/version-control.scm?id=70128b8afacf332b0aff69ebcad6868fd158e8ad'>tree</a><a href='/guix/commit/gnu/tests/version-control.scm?id=70128b8afacf332b0aff69ebcad6868fd158e8ad'>commit</a><a href='/guix/diff/gnu/tests/version-control.scm?id=70128b8afacf332b0aff69ebcad6868fd158e8ad'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/tests/version-control.scm'>
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<div class='path'>path: <a href='/guix/log/?id=70128b8afacf332b0aff69ebcad6868fd158e8ad'>root</a>/<a href='/guix/log/gnu?id=70128b8afacf332b0aff69ebcad6868fd158e8ad'>gnu</a>/<a href='/guix/log/gnu/tests?id=70128b8afacf332b0aff69ebcad6868fd158e8ad'>tests</a>/<a href='/guix/log/gnu/tests/version-control.scm?id=70128b8afacf332b0aff69ebcad6868fd158e8ad'>version-control.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/tests/version-control.scm?id=70128b8afacf332b0aff69ebcad6868fd158e8ad&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-11-07 12:07:41 +0100'>2020-11-07</span></td><td><a href='/guix/commit/gnu/tests/version-control.scm?id=de6b649f8031cc2fa45099a3c41d78c2e302fdf2'>tests: git-http: Avoid race condition.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/tests/version-control.scm (run-git-http-test)[test]("fcgiwrap
listens"): New test.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-10-18 01:12:22 +0200'>2018-10-18</span></td><td><a href='/guix/commit/gnu/tests/version-control.scm?id=39d7fdce453b0ca23ecbed72048647debbaa58a6'>services: dhcp-client: Deprecate 'dhcp-client-service' procedure.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/networking.scm (dhcp-client-service-type): Add default
value.
* gnu/system/examples/bare-bones.tmpl: Use (service
dhcp-client-service-type) instead of (dhcp-client-service).
* gnu/system/examples/beaglebone-black.tmpl: Likewise.
* gnu/tests/base.scm (%avahi-os): Likewise.
* gnu/tests/databases.scm (%memcached-os): Likewise.
(%mongodb-os): Likewise.
* gnu/tests/dict.scm (%dicod-os): Likewise.
* gnu/tests/mail.scm (%opensmtpd-os): Likewise.
(%exim-os): Likewise.
(%dovecot-os): Likewise.
* gnu/tests/messaging.scm (run-xmpp-test): Likewise.
(run-bitlbee-test): Likewise.
* gnu/tests/monitoring.scm (%prometheus-node-exporter-os): Likewise.
* gnu/tests/networking.scm (%inetd-os): Likewise.
(run-iptables-test): Likewise.
* gnu/tests/nfs.scm (%base-os): Likewise.
* gnu/tests/rsync.scm (%rsync-os): Likewise.
* gnu/tests/ssh.scm (run-ssh-test): Likewise.
* gnu/tests/version-control.scm (%cgit-os): Likewise.
(%git-http-os): Likewise.
(%gitolite-os): Likewise.
* gnu/tests/virtualization.scm (%libvirt-os): Likewise.
* gnu/tests/web.scm (%httpd-os): Likewise.
(%nginx-os): Likewise.
(%varnish-os): Likewise.
(%php-fpm-os): Likewise.
(%hpcguix-web-os): Likewise.
(%tailon-os): Likewise.
* tests/guix-system.sh: Likewise.
* doc/guix.texi (Networking Services): Document
'dhcp-client-service-type' and remove 'dhcp-client-service'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-10-02 08:11:17 +0100'>2018-10-02</span></td><td><a href='/guix/commit/gnu/tests/version-control.scm?id=f8e710684e5c3f866413dff825ba17bdffceac5d'>services: Add Gitolite.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/version-control.scm (&lt;gitolite-configuration&gt;,
&lt;gitolite-rc-file&gt;): New record types.
(gitolite-accounts, gitolite-activation): New procedures.
(gitolite-service-type): New variables.
* gnu/tests/version-control.scm (%gitolite-test-admin-keypair, %gitolite-os,
%test-gitolite): New variables.
(run-gitolite-test): New procedure.
* doc/guix.texi (Version Control): Document the gitolite service.
</span></span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2018-09-29 21:18:45 -0400'>2018-09-29</span></td><td><a href='/guix/commit/gnu/tests/version-control.scm?id=17bea1803cf706d8db053d8d73302a4455684d29'>Revert "services: Add Gitolite."</a><span class='msg-avail'>...<span class='msg-tooltip'>This reverts commit 258a6d944ed891fa92fa87a16731e5dfe0bac477.
</span></span></td><td>Mark H Weaver</td></tr>
<tr><td><span title='2018-09-28 21:00:18 +0100'>2018-09-28</span></td><td><a href='/guix/commit/gnu/tests/version-control.scm?id=258a6d944ed891fa92fa87a16731e5dfe0bac477'>services: Add Gitolite.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/version-control.scm (&lt;gitolite-configuration&gt;,
&lt;gitolite-rc-file&gt;): New record types.
(gitolite-accounts, gitolite-activation): New procedures.
(gitolite-service-type): New variables.
* gnu/tests/version-control.scm (%gitolite-test-admin-keypair, %gitolite-os,
%test-gitolite): New variables.
(run-gitolite-test): New procedure.
* doc/guix.texi (Version Control): Document the gitolite service.
</span></span></td><td>Christopher Baines</td></tr>