Add support for Rust C libraries.

Adds the ability for rust modules to be compiled as C libraries, and
allows cc modules to depend on these rust-generated modules. This also
means that soong-rust should not have any dependencies on soong-cc aside
from what's required for testing.

There's a couple small fixes included as well:

 - A bug in libNameFromFilePath that caused issues when library's had
 "lib" in their name.
 - VariantName is removed from rust library MutatedProperties since this
 was unused.

Bug: 140726209
Test: Soong tests pass.
Test: Example cc_binary can include a rust shared library as a dep.
Test: m crosvm.experimental
Change-Id: Ia7deed1345d2423001089014cc65ce7934123da4
diff --git a/cc/stl.go b/cc/stl.go
index f9273e1..101519b 100644
--- a/cc/stl.go
+++ b/cc/stl.go
@@ -20,13 +20,13 @@
 	"strconv"
 )
 
-func getNdkStlFamily(m *Module) string {
+func getNdkStlFamily(m LinkableInterface) string {
 	family, _ := getNdkStlFamilyAndLinkType(m)
 	return family
 }
 
-func getNdkStlFamilyAndLinkType(m *Module) (string, string) {
-	stl := m.stl.Properties.SelectedStl
+func getNdkStlFamilyAndLinkType(m LinkableInterface) (string, string) {
+	stl := m.SelectedStl()
 	switch stl {
 	case "ndk_libc++_shared":
 		return "libc++", "shared"