Remove unused mips workarounds.

This was never really finished, and hasn't been supported for years.

Test: treehugger
Change-Id: I21d4c3112aa8cf0c56e59f0cc19ff8725ef714b9

cc/ndk_library.go

@@ -133,8 +133,6 @@ func normalizeNdkApiLevel(ctx android.BaseModuleContext, apiLevel string,
 	firstArchVersions := map[android.ArchType]int{
 		android.Arm:    minVersion,
 		android.Arm64:  21,
-		android.Mips:   minVersion,
-		android.Mips64: 21,
 		android.X86:    minVersion,
 		android.X86_64: 21,
 	}