Fix foritfy test for clang update.

When doing checkbuild for make_fortify_compile_test.mk:
bionic/tests/clang_fortify_tests.cpp
error: 'error' diagnostics seen but not expected:
  Line 171: 'mempcpy' will always overflow; destination buffer has size 8, but size argument is 9
1 error generated.

Bug: 149839606
Test: run checkbuild.
Change-Id: I97371600f6183b5cee8c2a6b976f5bf33e1f781d
diff --git a/tests/clang_fortify_tests.cpp b/tests/clang_fortify_tests.cpp
index 018880f..715f9c8 100644
--- a/tests/clang_fortify_tests.cpp
+++ b/tests/clang_fortify_tests.cpp
@@ -167,6 +167,8 @@
     EXPECT_FORTIFY_DEATH(memcpy(small_buffer, large_buffer, sizeof(large_buffer)));
     // expected-error@+1{{will always overflow}}
     EXPECT_FORTIFY_DEATH(memmove(small_buffer, large_buffer, sizeof(large_buffer)));
+    // FIXME(gbiv): look into removing mempcpy's diagnose_if bits once the b/149839606 roll sticks.
+    // expected-error@+2{{will always overflow}}
     // expected-error@+1{{size bigger than buffer}}
     EXPECT_FORTIFY_DEATH(mempcpy(small_buffer, large_buffer, sizeof(large_buffer)));
     // expected-error@+1{{will always overflow}}