cmd/dist: execute misc/cgo/testso{,var} as regular tests, not host tests

These tests use runtime.GOOS and runtime.GOARCH to determine whether
to run, so must be built and run using the destination's — not the
host's — GOOS and GOARCH.

Updates #30228

Change-Id: I6774dacd01c68b395fca8ca61f70d5879270af8a
Reviewed-on: https://go-review.googlesource.com/c/164117
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>

src/cmd/dist/test.go

@@ -674,8 +674,8 @@ func (t *tester) registerTests() {
 	// recompile the entire standard library. If make.bash ran with
 	// special -gcflags, that's not true.
 	if t.cgoEnabled && gogcflags == "" {
-		t.registerHostTest("testso", "../misc/cgo/testso", "misc/cgo/testso", ".")
-		t.registerHostTest("testsovar", "../misc/cgo/testsovar", "misc/cgo/testsovar", ".")
+		t.registerTest("testso", "../misc/cgo/testso", t.goTest(), t.timeout(600))
+		t.registerTest("testsovar", "../misc/cgo/testsovar", t.goTest(), t.timeout(600))
 		if t.supportedBuildmode("c-archive") {
 			t.registerHostTest("testcarchive", "../misc/cgo/testcarchive", "misc/cgo/testcarchive", ".")
 		}