Add BUILD(_HOST)?_FUZZ_TEST.

These are tests that use LLVM's libFuzzer for testing with a
sanitizer.

Bug: http://b/22850550
Change-Id: I6eeaff7877b7dd0c30f8910c6f27f5278b27a83d
diff --git a/core/config.mk b/core/config.mk
index 498c793..fea3d4b 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -85,6 +85,8 @@
 BUILD_NATIVE_TEST := $(BUILD_SYSTEM)/native_test.mk
 BUILD_NATIVE_BENCHMARK := $(BUILD_SYSTEM)/native_benchmark.mk
 BUILD_HOST_NATIVE_TEST := $(BUILD_SYSTEM)/host_native_test.mk
+BUILD_FUZZ_TEST := $(BUILD_SYSTEM)/fuzz_test.mk
+BUILD_HOST_FUZZ_TEST := $(BUILD_SYSTEM)/host_fuzz_test.mk
 
 BUILD_SHARED_TEST_LIBRARY := $(BUILD_SYSTEM)/shared_test_lib.mk
 BUILD_HOST_SHARED_TEST_LIBRARY := $(BUILD_SYSTEM)/host_shared_test_lib.mk