misc/cgo: move easy tests to cmd/cgo/internal

This moves most misc/cgo tests to cmd/cgo/internal. This is mostly a
trivial rename and updating dist/test.go for the new paths, plus
excluding these packages from regular dist test registration. A few
tests were sensitive to what path they ran in, so we update those.

This will let these tests access facilities in internal/testenv.

For #37486.

Change-Id: I3ed417c7c22d9b667f2767c0cb1f59118fcd4af6
Reviewed-on: https://go-review.googlesource.com/c/go/+/492720
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/cgo/doc.go

@@ -26,7 +26,7 @@ declared in the preamble may be used, even if they start with a
 lower-case letter. Exception: static variables in the preamble may
 not be referenced from Go code; static functions are permitted.
 
-See $GOROOT/misc/cgo/stdio and $GOROOT/misc/cgo/gmp for examples. See
+See $GOROOT/cmd/cgo/internal/teststdio and $GOROOT/misc/cgo/gmp for examples. See
 "C? Go? Cgo!" for an introduction to using cgo:
 https://golang.org/doc/articles/c_go_cgo.html.
 

src/cmd/cgo/internal/testcarchive/testdata/main2.c

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // Test installing a signal handler before the Go code starts.
-// This is a lot like misc/cgo/testcshared/main4.c.
+// This is a lot like ../testcshared/main4.c.
 
 #include <setjmp.h>
 #include <signal.h>

src/cmd/cgo/internal/testcarchive/testdata/main3.c

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // Test os/signal.Notify and os/signal.Reset.
-// This is a lot like misc/cgo/testcshared/main5.c.
+// This is a lot like ../testcshared/main5.c.
 
 #include <signal.h>
 #include <stdio.h>

src/cmd/cgo/internal/testcshared/testdata/main4.c

@@ -4,7 +4,7 @@
 
 // Test that a signal handler that uses up stack space does not crash
 // if the signal is delivered to a thread running a goroutine.
-// This is a lot like misc/cgo/testcarchive/main2.c.
+// This is a lot like ../testcarchive/main2.c.
 
 #include <setjmp.h>
 #include <signal.h>

src/cmd/cgo/internal/testcshared/testdata/main5.c

@@ -4,7 +4,7 @@
 
 // Test that a signal handler works in non-Go code when using
 // os/signal.Notify.
-// This is a lot like misc/cgo/testcarchive/main3.c.
+// This is a lot like ../testcarchive/main3.c.
 
 #include <signal.h>
 #include <stdio.h>

src/cmd/cgo/internal/testfortran/fortran_test.go

@@ -63,7 +63,7 @@ func TestFortran(t *testing.T) {
 	}
 
 	// Do a test build that doesn't involve Go FORTRAN support.
-	fcArgs := append([]string{"helloworld/helloworld.f90", "-o", "/dev/null"}, fcExtra...)
+	fcArgs := append([]string{"testdata/helloworld/helloworld.f90", "-o", "/dev/null"}, fcExtra...)
 	t.Logf("%s %s", fc, fcArgs)
 	if err := exec.Command(fc, fcArgs...).Run(); err != nil {
 		t.Skipf("skipping Fortran test: could not build helloworld.f90 with %s: %s", fc, err)

src/cmd/cgo/internal/testplugin/plugin_test.go

@@ -48,7 +48,7 @@ func testMain(m *testing.M) int {
 	if err != nil {
 		log.Fatal(err)
 	}
-	goroot = filepath.Join(cwd, "../../..")
+	goroot = filepath.Join(cwd, "../../../../..")
 
 	// Copy testdata into GOPATH/src/testplugin, along with a go.mod file
 	// declaring the same path.