Add support for CMakefile generation

Test: Manually generated CMakeLists.txt for gui/ui/aapt2.

Change-Id: I7dedc300c1e50b8e39bc58091b650c0bbe2c62da

cc/compiler.go

@@ -123,10 +123,20 @@ type baseCompiler struct {
 	Properties BaseCompilerProperties
 	Proto      ProtoProperties
 	deps       android.Paths
+	srcs       android.Paths
+	flags      builderFlags
 }
 
 var _ compiler = (*baseCompiler)(nil)
 
+type CompiledInterface interface {
+	Srcs() android.Paths
+}
+
+func (compiler *baseCompiler) Srcs() android.Paths {
+	return compiler.srcs
+}
+
 func (compiler *baseCompiler) appendCflags(flags []string) {
 	compiler.Properties.Cflags = append(compiler.Properties.Cflags, flags...)
 }
@@ -429,6 +439,9 @@ func (compiler *baseCompiler) compile(ctx ModuleContext, flags Flags, deps PathD
 
 	compiler.deps = pathDeps
 
+	// Save src, buildFlags and context
+	compiler.srcs = srcs
+
 	// Compile files listed in c.Properties.Srcs into objects
 	objs := compileObjs(ctx, buildFlags, "", srcs, compiler.deps)