Revert "Add sdk mutator for native modules"

Revert submission 1242911-sdk_version_variant

Reason for revert: b/153394225
Reverted Changes:
Ife99745fb:Use libnativewindow for platform variant of libagq...
I1bae84c43:Use libnativewindow for platform variant of androi...
I6e6021ed3:Use stl to depend on libc++
Ife99745fb:Use libnativewindow for platform variant of libRSS...
I2c9f439b9:Fix static dependency on libprotobuf-cpp-lite-ndk
Iff2aff9cf:Set sdk_version for cc_genrules used by modules wi...
I7d72934aa:Add sdk mutator for native modules
Ief378a007:Use sdk variant of Soong modules when LOCAL_SDK_VE...

Bug: 149591340
Change-Id: I798fa902c779469c6382b6699351e5d12bf14785
Fixes: 153394225
diff --git a/cc/stl.go b/cc/stl.go
index 4e74c7f..8113f72 100644
--- a/cc/stl.go
+++ b/cc/stl.go
@@ -115,13 +115,9 @@
 			switch s {
 			case "libc++", "libc++_static":
 				return s
-			case "c++_shared":
-				return "libc++"
-			case "c++_static":
-				return "libc++_static"
 			case "none":
 				return ""
-			case "", "system":
+			case "":
 				if ctx.static() {
 					return "libc++_static"
 				} else {