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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<tr><td><span title='2020-04-16 23:41:52 +0200'>2020-04-16</span></td><td><a href='/guix/commit/doc/package-hello.json?id=c9f321e52a99dea93fcc099372ea0167150b9aac'>doc: Document building and installing from JSON files.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/guix.texi (Invoking guix package): Augment pargraphs for
"--install-from-file".
(Invoking guix build): Document building from JSON files.
* doc/package-hello.json: New file.
* doc/local.mk (EXTRA_DIST): Add it.
</span></span></td><td>Ricardo Wurmus</td></tr>