Use the platform -std= for sdk_version.

Bug: http://b/72571399
Test: builds
Change-Id: I294cfadb7de54b1ae648e02ac9af34ed7a7405d8

cc/compiler.go

@@ -397,7 +397,6 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags, deps
 		flags.GlobalFlags = append(flags.GlobalFlags, tc.ToolchainCflags())
 	}
 
-	if !ctx.useSdk() {
 	cStd := config.CStdVersion
 	if String(compiler.Properties.C_std) == "experimental" {
 		cStd = config.ExperimentalCStdVersion
@@ -420,10 +419,9 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags, deps
 		// GCC uses an invalid C++14 ABI (emits calls to
 		// __cxa_throw_bad_array_length, which is not a valid C++ RT ABI).
 		// http://b/25022512
-			cppStd = config.GccCppStdVersion
-		} else if ctx.Host() && !flags.Clang {
 		// The host GCC doesn't support C++14 (and is deprecated, so likely
-			// never will). Build these modules with C++11.
+		// never will).
+		// Build these modules with C++11.
 		cppStd = config.GccCppStdVersion
 	}
 
@@ -434,7 +432,6 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags, deps
 
 	flags.ConlyFlags = append([]string{"-std=" + cStd}, flags.ConlyFlags...)
 	flags.CppFlags = append([]string{"-std=" + cppStd}, flags.CppFlags...)
-	}
 
 	if ctx.useVndk() {
 		flags.CFlags = append(flags.CFlags, esc(compiler.Properties.Target.Vendor.Cflags)...)

cc/stl.go

@@ -176,8 +176,7 @@ func (stl *stl) flags(ctx ModuleContext, flags Flags) Flags {
 		ndkSrcRoot := android.PathForSource(ctx, "prebuilts/ndk/current/sources/cxx-stl/system/include")
 		flags.CFlags = append(flags.CFlags, "-isystem "+ndkSrcRoot.String())
 	case "ndk_libc++_shared", "ndk_libc++_static":
-		// TODO(danalbert): This really shouldn't be here...
-		flags.CppFlags = append(flags.CppFlags, "-std=c++11")
+		// Nothing.
 	case "":
 		// None or error.
 		if !ctx.toolchain().Bionic() {