Rust: Vendor support for Rust static libraries.

We don't have Rust VNDK support yet, but static linkage can be
supported in the interim. This adds support for making rust_ffi_static
libraries available to CC vendor modules.

Since rust_ffi_static modules will link against rlibs, we allow rlib
linkage into vendor as well, but only for the variants which use the
rlib libstd.

Bug: 172525289
Test: New Soong tests pass
Test: Example vendor cc_binary links against rust_ffi_static module.
Change-Id: Idf3aeb51e32293866f1ad965e329aa6b9e0bf2ef

rust/library.go

@@ -601,6 +601,11 @@ func LibraryMutator(mctx android.BottomUpMutatorContext) {
 			v.(*Module).compiler.(libraryInterface).setRlib()
 		case dylibVariation:
 			v.(*Module).compiler.(libraryInterface).setDylib()
+			if v.(*Module).ModuleBase.ImageVariation().Variation != android.CoreVariation {
+				// TODO(b/165791368)
+				// Disable dylib non-core variations until we support these.
+				v.(*Module).Disable()
+			}
 		case "source":
 			v.(*Module).compiler.(libraryInterface).setSource()
 			// The source variant does not produce any library.
@@ -637,6 +642,12 @@ func LibstdMutator(mctx android.BottomUpMutatorContext) {
 				dylib := modules[1].(*Module)
 				rlib.compiler.(libraryInterface).setRlibStd()
 				dylib.compiler.(libraryInterface).setDylibStd()
+				if dylib.ModuleBase.ImageVariation().Variation != android.CoreVariation {
+					// TODO(b/165791368)
+					// Disable rlibs that link against dylib-std on non-core variations until non-core dylib
+					// variants are properly supported.
+					dylib.Disable()
+				}
 				rlib.Properties.SubName += RlibStdlibSuffix
 				dylib.Properties.SubName += DylibStdlibSuffix
 			}