KNOWN_BROKEN/FAILING does not work for gtests.

Instead disable the test in the gtest file.

Change-Id: Iede5de7ca572c9454437981a5fa63cda444d0497
diff --git a/build/Android.gtest.mk b/build/Android.gtest.mk
index 9e261a8..71a55bb 100644
--- a/build/Android.gtest.mk
+++ b/build/Android.gtest.mk
@@ -697,11 +697,6 @@
 $(eval $(call define-test-art-gtest-combination,host,HOST,valgrind-,$(2ND_ART_PHONY_TEST_HOST_SUFFIX)))
 endif
 
-ifeq (mips,$(TARGET_ARCH))
-  # b/24596015
-  ART_TEST_KNOWN_BROKEN += test-art-target-gtest-imgdiag_test32
-endif
-
 # Clear locally defined variables.
 define-art-gtest-rule-target :=
 define-art-gtest-rule-host :=
diff --git a/imgdiag/imgdiag_test.cc b/imgdiag/imgdiag_test.cc
index 1ac7930..82bc8b9 100644
--- a/imgdiag/imgdiag_test.cc
+++ b/imgdiag/imgdiag_test.cc
@@ -109,11 +109,12 @@
   std::string boot_image_location_;
 };
 
-#if defined (ART_TARGET)
+#if defined (ART_TARGET) && !defined(__mips__)
 TEST_F(ImgDiagTest, ImageDiffPidSelf) {
 #else
 // Can't run this test on the host, it will fail when trying to open /proc/kpagestats
 // because it's root read-only.
+// Also test fails on mips. b/24596015.
 TEST_F(ImgDiagTest, DISABLED_ImageDiffPidSelf) {
 #endif
   // Invoke 'img_diag' against the current process.