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 ()
ystem/keyboard.scm?id=6d13c785fc49171027b3baabab9c6fdb93dd422c'>tree</a><a href='/guix/commit/gnu/system/keyboard.scm?id=6d13c785fc49171027b3baabab9c6fdb93dd422c'>commit</a><a href='/guix/diff/gnu/system/keyboard.scm?id=6d13c785fc49171027b3baabab9c6fdb93dd422c'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/system/keyboard.scm'>
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<div class='path'>path: <a href='/guix/log/?id=6d13c785fc49171027b3baabab9c6fdb93dd422c'>root</a>/<a href='/guix/log/gnu?id=6d13c785fc49171027b3baabab9c6fdb93dd422c'>gnu</a>/<a href='/guix/log/gnu/system?id=6d13c785fc49171027b3baabab9c6fdb93dd422c'>system</a>/<a href='/guix/log/gnu/system/keyboard.scm?id=6d13c785fc49171027b3baabab9c6fdb93dd422c'>keyboard.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/system/keyboard.scm?id=6d13c785fc49171027b3baabab9c6fdb93dd422c&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-04-06 00:14:13 +0200'>2020-04-06</span></td><td><a href='/guix/commit/gnu/system/keyboard.scm?id=2729cb406d9f3e9eb22cc660f887138134edb3a8'>system: Allow for comma-separated keyboard layouts.</a><span class='msg-avail'>...<span class='msg-tooltip'>Reported by Florian Pelz &lt;pelzflorian@pelzflorian.de&gt;.

* gnu/bootloader/grub.scm (keyboard-layout-file): Replace commas with
hyphens in the first argument to 'computed-file'.
* gnu/system/keyboard.scm (keyboard-layout-&gt;console-keymap): Likewise.
* doc/guix.texi (Keyboard Layout): Add example.
</span></span></td><td>Ludovic Courtès</td></tr>