Enable safe ICF with LLD.

Support for safe ICF was added to LLD in LLVM r337429. This reduces
the size of sailfish system.img by 7.6MB.

The address-significance tables created by Clang to support LLD's
implementation of safe ICF are incompatible with ld -r. Therefore we
need to pass -fno-addrsig to the compiler to prevent it from creating
an address-significance table when building a cc_object.

Change-Id: I83e28741e6b3cdf09566447d2658ce48594f2074

cc/object.go

@@ -39,6 +39,10 @@ func ObjectFactory() android.Module {
 		baseLinker: NewBaseLinker(nil),
 	}
 	module.compiler = NewBaseCompiler()
+
+	// Clang's address-significance tables are incompatible with ld -r.
+	module.compiler.appendCflags([]string{"-fno-addrsig"})
+
 	module.stl = &stl{}
 	return module.Init()
 }