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 ()
u/packages/gnu-doc.scm?id=1fa3b736186f4afae1e9fee337c4dd7cb84d2630'>tree</a><a href='/guix/commit/gnu/packages/gnu-doc.scm?id=1fa3b736186f4afae1e9fee337c4dd7cb84d2630'>commit</a><a href='/guix/diff/gnu/packages/gnu-doc.scm?id=1fa3b736186f4afae1e9fee337c4dd7cb84d2630'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/gnu-doc.scm'>
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<div class='path'>path: <a href='/guix/log/?id=1fa3b736186f4afae1e9fee337c4dd7cb84d2630'>root</a>/<a href='/guix/log/gnu?id=1fa3b736186f4afae1e9fee337c4dd7cb84d2630'>gnu</a>/<a href='/guix/log/gnu/packages?id=1fa3b736186f4afae1e9fee337c4dd7cb84d2630'>packages</a>/<a href='/guix/log/gnu/packages/gnu-doc.scm?id=1fa3b736186f4afae1e9fee337c4dd7cb84d2630'>gnu-doc.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/packages/gnu-doc.scm?id=1fa3b736186f4afae1e9fee337c4dd7cb84d2630&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
86'>patches</a>/<a href='/guix/log/gnu/packages/patches/audiofile-Fix-multiply-overflow-sfconvert.patch?id=aa13c5657d4f8b5dd52beda88a9a8ccc59ebca86'>audiofile-Fix-multiply-overflow-sfconvert.patch</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/packages/patches/audiofile-Fix-multiply-overflow-sfconvert.patch?id=aa13c5657d4f8b5dd52beda88a9a8ccc59ebca86&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-12-26 16:44:53 +0100'>2019-12-26</span></td><td><a href='/guix/commit/gnu/packages/patches/audiofile-Fix-multiply-overflow-sfconvert.patch?id=a8e149434eb1500026256747b4ed21b8bab95926'>gnu: Add audiofile.</a><span class='msg-avail'>...<span class='msg-tooltip'>Patches should fix all CVEs reported by `guix lint`:
CVE-2015-7747; CVE-2017-6827, CVE-2017-6828, CVE-2017-6829,
CVE-2017-6830, CVE-2017-6831, CVE-2017-6832, CVE-2017-6833,
CVE-2017-6834, CVE-2017-6835, CVE-2017-6836, CVE-2017-6837,
CVE-2017-6838, CVE-2017-6839; CVE-2018-13440; CVE-2018-17095

Since the patches do not reference to CVEs, it's a bit hard to tell which
patch actually closes which CVE.  Debian reports all these to be closed by
the patches below and NixPkgs provides references.

* gnu/packages/audio.scm (audiofile): New variable.
* gnu/packages/patches/audiofile-fix-datatypes-in-tests.patch,
  gnu/packages/patches/audiofile-fix-sign-conversion.patch,
  gnu/packages/patches/audiofile-CVE-2015-7747.patch,
  gnu/packages/patches/audiofile-CVE-2018-13440.patch,
  gnu/packages/patches/audiofile-CVE-2018-17095.patch,
  gnu/packages/patches/audiofile-Check-the-number-of-coefficients.patch,
  gnu/packages/patches/audiofile-Fail-on-error-in-parseFormat.patch,
  gnu/packages/patches/audiofile-Fix-index-overflow-in-IMA.cpp.patch,
  gnu/packages/patches/audiofile-Fix-multiply-overflow-sfconvert.patch,
  gnu/packages/patches/audiofile-Fix-overflow-in-MSADPCM-decodeSam.patch,
  gnu/packages/patches/audiofile-division-by-zero-BlockCodec-runPull.patch,
  gnu/packages/patches/audiofile-hurd.patch,
  gnu/packages/patches/audiofile-signature-of-multiplyCheckOverflow.patch:
  New files.
* gnu/local.mk: Add them.
</span></span></td><td>Hartmut Goebel</td></tr>