Stop building MIPS ABIs for the NDK.

Test: build/soong/scripts/build-ndk-prebuilts.sh
Bug: https://github.com/android-ndk/ndk/issues/272
Change-Id: Ia8d48b1ecef5e1a3b239e2817eeed5dbe43e52ef
diff --git a/android/arch.go b/android/arch.go
index f8317bb..5ea9759 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -973,8 +973,6 @@
 	return []archConfig{
 		{"arm", "armv5te", "", []string{"armeabi"}},
 		{"arm64", "armv8-a", "", []string{"arm64-v8a"}},
-		{"mips", "mips32-fp", "", []string{"mips"}},
-		{"mips64", "mips64r6", "", []string{"mips64"}},
 		{"x86", "", "", []string{"x86"}},
 		{"x86_64", "", "", []string{"x86_64"}},
 	}