Support "memtag_heap" sanitizer.

Memtag_heap adds an ELF note that enables MTE heap tagging in
bionic/scudo. Ignored on non-executables. With diagnostic
(diag:{memtag_heap:true}) enables the SYNC mode, otherwise - ASYNC mode.

Memtag_heap defaults to set (with diag) on cc_test targets, unset
otherwise. Ignored on non MTE-compatible hardware.

Bug: b/135772972
Test: soong tests

Change-Id: I88fd0f159e609e17bd13487749980a1ba02cb91c

cc/test.go

@@ -236,6 +236,10 @@ func (test *testDecorator) gtest() bool {
 	return BoolDefault(test.Properties.Gtest, true)
 }
 
+func (test *testDecorator) testBinary() bool {
+	return true
+}
+
 func (test *testDecorator) linkerFlags(ctx ModuleContext, flags Flags) Flags {
 	if !test.gtest() {
 		return flags