More gtest overrides to fix OSX GN build

Review-Url: https://codereview.chromium.org/1951873003
diff --git a/build_overrides/gtest.gni b/build_overrides/gtest.gni
index 6089962..bf30fb1 100644
--- a/build_overrides/gtest.gni
+++ b/build_overrides/gtest.gni
@@ -7,3 +7,9 @@
 
 # Exclude support for platform-specific operations across unit tests.
 gtest_include_platform_test = false
+
+# Exclude support for testing Objective C code on OS X and iOS.
+gtest_include_objc_support = false
+
+# Exclude support for flushing coverage files on iOS.
+gtest_include_ios_coverage = false