Make sure the build system honors C_INCLUDE_PATH and LIBRARY_PATH when
looking for headers and libraries.

--- a/setup.py	2015-10-07 23:32:58.891329173 +0200
+++ b/setup.py	2015-10-07 23:46:29.653349924 +0200
@@ -676,15 +676,15 @@
         # if a file is found in one of those directories, it can
         # be assumed that no additional -I,-L directives are needed.
         if not CROSS_COMPILING:
-            self.lib_dirs = self.compiler.library_dirs + system_lib_dirs
-            self.inc_dirs = self.compiler.include_dirs + system_include_dirs
+            self.lib_dirs = os.getenv('LIBRARY_PATH', '').split(os.pathsep)
+            self.inc_dirs = os.getenv('C_INCLUDE_PATH', '').split(os.pathsep)
         else:
             # Add the sysroot paths. 'sysroot' is a compiler option used to
             # set the logical path of the standard system headers and
             # libraries.
-            self.lib_dirs = (self.compiler.library_dirs +
+            self.lib_dirs = (os.getenv('CROSS_LIBRARY_PATH', '').split(os.pathsep) +
                              sysroot_paths(('LDFLAGS', 'CC'), system_lib_dirs))
-            self.inc_dirs = (self.compiler.include_dirs +
+            self.inc_dirs = (os.getenv('CROSS_C_INCLUDE_PATH', '').split(os.pathsep) +
                              sysroot_paths(('CPPFLAGS', 'CFLAGS', 'CC'),
                                            system_include_dirs))
 
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<div class='path'>path: <a href='/guix/log/?id=58974e7b1971c9795ab6365b8e80e5140ceba9e5'>root</a>/<a href='/guix/log/etc?id=58974e7b1971c9795ab6365b8e80e5140ceba9e5'>etc</a>/<a href='/guix/log/etc/system-tests.scm?id=58974e7b1971c9795ab6365b8e80e5140ceba9e5'>system-tests.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/etc/system-tests.scm?id=58974e7b1971c9795ab6365b8e80e5140ceba9e5&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-08-09 15:16:06 +0200'>2022-08-09</span></td><td><a href='/guix/commit/etc/system-tests.scm?id=5bce4c82422de6beb3ce6120ba1592be898c2b72'>build-system: Add 'channel-build-system'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/ci.scm (channel-build-system, channel-source-&gt;package): Remove.
* gnu/packages/package-management.scm (channel-source-&gt;package): New
procedure, moved from (gnu ci).
* guix/build-system/channel.scm: New file, with code moved from (gnu ci).
* doc/guix.texi (Build Systems): Document it.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-07-10 23:57:14 +0200'>2022-07-10</span></td><td><a href='/guix/commit/etc/system-tests.scm?id=9fdc4b6c283c5aa5cf10205d87fb2c58b829b9d0'>monads: Add 'mparameterize'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/system-tests.scm (mparameterize): Move to...
* guix/monads.scm (mparameterize): ... here.
* tests/monads.scm ("mparameterize"): New test.
* .dir-locals.el (c-mode): Add it.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-04-11 00:25:33 +0200'>2022-04-11</span></td><td><a href='/guix/commit/etc/system-tests.scm?id=dbde386794cb5f4773b94a20ef585ca0f881544a'>tests: System tests really parameterize 'current-guix-package'.</a><span class='msg-avail'>...<span class='msg-tooltip'>Until now, 'current-guix-package' was parameterized in the wrong
context.  Thus, 'current-guix' would end up building a variant of the
'guix' package instead of the package returned by
'channel-source-&gt;package', which is much less expensive to build.

* etc/system-tests.scm (mparameterize): New macro.
(tests-for-current-guix): Change the 'value' field of each &lt;system-test&gt;
record to parameterize 'current-guix-package' for good.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-23 00:06:58 +0100'>2020-03-23</span></td><td><a href='/guix/commit/etc/system-tests.scm?id=8b18f5cb309f670b08ad35df6425f4e9e19d8a82'>tests: Use the same source as ci.guix.gnu.org.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/system-tests.scm (system-test-manifest): In 'local-file' call, use
a name that is a function of COMMIT to match what Cuirass does.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-05 16:33:38 +0100'>2020-03-05</span></td><td><a href='/guix/commit/etc/system-tests.scm?id=5ec4156bbcaec8337f78411204d59e59e706103b'>tests: Add a manifest for system tests.</a><span class='msg-avail'>...<span class='msg-tooltip'>The manifest can be passed to 'guix build -m', 'guix weather -m', and so
on.  It can also be passed to an installed 'guix' (without
./pre-inst-env), with the exception so far of installation tests.

* build-aux/run-system-tests.scm: Remove.  Move interesting bits move
to...
* etc/system-tests.scm: ... here.  New file.
* Makefile.am (EXTRA_DIST): Remove 'build-aux/run-system-tests.scm' and
add 'etc/system-tests.scm'.
(check-system): Rewrite to run 'guix build -m etc/system-tests.scm'.
</span></span></td><td>Ludovic Courtès</td></tr>