cc: export Stripper struct

The cc stripping logic can be reused for Rust. Export the Stripper
structure for that purpose. Extract the strip-related flags from
builderFlags into StripFlags. Add the method flagsToStripFlags
(similarly to flagsToBuilderFlags).

Add the helper method disableStripping on libraryDecorator.

Test: m
Bug: 153430439
Change-Id: I11aef1abb8d498a4c1672500a7398279edf7f548

cc/util.go

@@ -100,6 +100,10 @@ func flagsToBuilderFlags(in Flags) builderFlags {
 	}
 }
 
+func flagsToStripFlags(in Flags) StripFlags {
+	return StripFlags{Toolchain: in.Toolchain}
+}
+
 func addPrefix(list []string, prefix string) []string {
 	for i := range list {
 		list[i] = prefix + list[i]