Add sdk version workaround for libclang_rt

libclang_rt.*.so depends on libc++, which is not a part of NDK.  Thus,
this workaround must be added in order not to break the build when the
prebuilt dependencies are checked.

Bug: 121358700
Test: make checkbuild
Change-Id: Icaeb7adf96fb72829053e198b659ebcb19a035fc
diff --git a/cc/cc.go b/cc/cc.go
index 1b5e8b1..f107968 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -1315,6 +1315,13 @@
 		// the NDK.
 		return
 	}
+
+	if strings.HasPrefix(ctx.ModuleName(), "libclang_rt.") && to.Name() == "libc++" {
+		// Bug: http://b/121358700 - Allow libclang_rt.* shared libraries (with sdk_version)
+		// to link to libc++ (non-NDK and without sdk_version).
+		return
+	}
+
 	if String(to.Properties.Sdk_version) == "" {
 		// NDK code linking to platform code is never okay.
 		ctx.ModuleErrorf("depends on non-NDK-built library %q",