Remove unnecessary DeviceUsesClang.

This build function is unnecessary now that GCC is completely
unsupported for Android platform builds. It is similar to
USE_CLANG_PLATFORM_BUILD from the build/make side of things.

Bug: http://b/64032869
Test: Builds
Change-Id: Iddf5f91cc997c337c77a644265cb8dc4e5a915b4

cc/cc.go

@@ -947,13 +947,7 @@ func (c *Module) clang(ctx BaseModuleContext) bool {
 	clang := Bool(c.Properties.Clang)
 
 	if c.Properties.Clang == nil {
-		if ctx.Host() {
-			clang = true
-		}
-
-		if ctx.Device() && ctx.Config().DeviceUsesClang() {
-			clang = true
-		}
+		clang = true
 	}
 
 	if !c.toolchain(ctx).ClangSupported() {