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))
 
tests/status.scm?id=02fad8089efbc9d5fd33b04ae5f840dbbb36b71b'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/status.scm'>
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<div class='path'>path: <a href='/guix/log/?id=02fad8089efbc9d5fd33b04ae5f840dbbb36b71b'>root</a>/<a href='/guix/log/tests?id=02fad8089efbc9d5fd33b04ae5f840dbbb36b71b'>tests</a>/<a href='/guix/log/tests/status.scm?id=02fad8089efbc9d5fd33b04ae5f840dbbb36b71b'>status.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/tests/status.scm?id=02fad8089efbc9d5fd33b04ae5f840dbbb36b71b&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-06-26 23:19:14 +0200'>2022-06-26</span></td><td><a href='/guix/commit/tests/status.scm?id=f99f00fc814a3e1a3e1cedb5059c896e3303677c'>status: Relay "updating substitutes" messages.</a><span class='msg-avail'>...<span class='msg-tooltip'>Until now, those messages would be accumulated and displayed all at
once, when a '\n' was finally emitted by 'guix substitute'.  In the
meantime, clients would remain silent.

* guix/status.scm (bytevector-index): Change 'number' parameter to
'numbers' and adjust accordingly.
(build-event-output-port): Pass both #\newline and #\return to
'bytevector-index'.
* tests/status.scm ("build-output-port, daemon messages with LF"): New
test.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-06-26 23:19:13 +0200'>2022-06-26</span></td><td><a href='/guix/commit/tests/status.scm?id=c31605b58228dbd10c819311a17341a22c9e5118'>status: Change tests from SRFI-11 to SRFI-71.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/status.scm: Use SRFI-71 'let' instead of SRFI-11 'let-values'.
</span></span></td><td>Ludovic Courtès</td></tr>