Bump the platform default up to C17.

This is already the "default default" for gcc and clang.

Bug: http://b/232413369
Test: treehugger
Change-Id: I3c0df7c63e8fca1b7692ad867d349a645559c209

cc/cc_test.go

@@ -4981,7 +4981,7 @@ func TestIncludeDirectoryOrdering(t *testing.T) {
 	cppOnly := []string{"-fPIC", "${config.CommonGlobalCppflags}", "${config.DeviceGlobalCppflags}", "${config.ArmCppflags}"}
 
 	cflags := []string{"-Werror", "-std=candcpp"}
-	cstd := []string{"-std=gnu11", "-std=conly"}
+	cstd := []string{"-std=gnu17", "-std=conly"}
 	cppstd := []string{"-std=gnu++17", "-std=cpp", "-fno-rtti"}
 
 	lastIncludes := []string{