Only output make targets for uninstallable static libs in the APEX
unavailable-to-platform case.

This removes the special case added in https://r.android.com/1274763
from SkipInstall(), so that it doesn't cause conflicting AndroidMk
entries when a cc_prebuilt_library_static module has prefer:true and
the corresponding source module exists.

Test: `m` in a tree with a snapshot created from art-module-sdk where
  the libartimagevalues module has prefer:true
Bug: 151303681
Change-Id: I651ae325753b707296892adb4cae80daaddb6af2
diff --git a/cc/installer.go b/cc/installer.go
index 0b4a68c..e551c63 100644
--- a/cc/installer.go
+++ b/cc/installer.go
@@ -107,6 +107,6 @@
 	return String(installer.Properties.Relative_install_path)
 }
 
-func (installer *baseInstaller) skipInstall(mod *Module) {
-	mod.ModuleBase.SkipInstall()
+func (installer *baseInstaller) makeUninstallable(mod *Module) {
+	mod.ModuleBase.MakeUninstallable()
 }