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/cc.go

@@ -420,6 +420,7 @@ type VendorProperties struct {
 type ModuleContextIntf interface {
 	static() bool
 	staticBinary() bool
+	testBinary() bool
 	header() bool
 	binary() bool
 	object() bool
@@ -1261,6 +1262,10 @@ func (ctx *moduleContextImpl) staticBinary() bool {
 	return ctx.mod.staticBinary()
 }
 
+func (ctx *moduleContextImpl) testBinary() bool {
+	return ctx.mod.testBinary()
+}
+
 func (ctx *moduleContextImpl) header() bool {
 	return ctx.mod.Header()
 }
@@ -2961,6 +2966,15 @@ func (c *Module) staticBinary() bool {
 	return false
 }
 
+func (c *Module) testBinary() bool {
+	if test, ok := c.linker.(interface {
+		testBinary() bool
+	}); ok {
+		return test.testBinary()
+	}
+	return false
+}
+
 // Header returns true if the module is a header-only variant. (See cc/library.go header()).
 func (c *Module) Header() bool {
 	if h, ok := c.linker.(interface {