Make library/header paths visible to cmd/go script tests, which is necessary for
cgo/gccgo tests to work correctly

diff --git a/src/cmd/go/script_test.go b/src/cmd/go/script_test.go
index dfaa40548e..9d0f0e9bcd 100644
--- a/src/cmd/go/script_test.go
+++ b/src/cmd/go/script_test.go
@@ -100,6 +100,10 @@ const (
 var extraEnvKeys = []string{
 	"SYSTEMROOT",         // must be preserved on Windows to find DLLs; golang.org/issue/25210
 	"WINDIR",             // must be preserved on Windows to be able to run PowerShell command; golang.org/issue/30711
+	"CPATH",
+	"C_INCLUDE_PATH",
+	"CPLUS_INCLUDE_PATH",
+	"LIBRARY_PATH",
 	"LD_LIBRARY_PATH",    // must be preserved on Unix systems to find shared libraries
 	"CC",                 // don't lose user settings when invoking cgo
 	"GO_TESTING_GOTOOLS", // for gccgo testing
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<div class='path'>path: <a href='/guix/log/?id=69dde4e354efee56422eb3527691b0714b596b49'>root</a>/<a href='/guix/log/TODO?id=69dde4e354efee56422eb3527691b0714b596b49'>TODO</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/TODO?id=69dde4e354efee56422eb3527691b0714b596b49&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-01-21 09:59:41 +0100'>2019-01-21</span></td><td><a href='/guix/commit/TODO?id=b93d2602f72dbbd9334a4f5c75b8721e1f2fa35a'>Update 'TODO'</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2019-01-17 14:11:15 +0100'>2019-01-17</span></td><td><a href='/guix/commit/TODO?id=11b68c90cd89288906c595d5c31a0413ed8a496f'>Update 'TODO'.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2016-09-01 14:57:03 +0200'>2016-09-01</span></td><td><a href='/guix/commit/TODO?id=e5cd149f681cc8d285da6c7638b70a43b333f337'>Update 'TODO'.</a><span class='msg-avail'>...</span></td><td>Vincent Legoll</td></tr>
mmit/doc/he-config-bare-bones.scm?id=0e8d2df0f1a4ab25c482e1c427c54e19903e62f3'>Move (gnu home-services) to (gnu home services).</a><span class='msg-avail'>...</span></td><td>Oleg Pykhalov</td></tr>
<tr><td><span title='2021-10-08 15:36:18 +0300'>2021-10-08</span></td><td><a href='/guix/commit/doc/he-config-bare-bones.scm?id=ba8ddb348045f81f061a1c7f51c0f7c2b0024e71'>gnu: Move (gnu home-services) to (gnu home services).</a><span class='msg-avail'>...</span></td><td>Oleg Pykhalov</td></tr>
<tr><td><span title='2021-09-09 20:26:51 +0300'>2021-09-09</span></td><td><a href='/guix/commit/doc/he-config-bare-bones.scm?id=aaffa43c1752e062934580f55616e0380963a1be'>doc: Add Guix Home documentation.</a><span class='msg-avail'>...</span></td><td>Andrew Tropin</td></tr>