Revert "Revert "Re-enable Clang's -Wpessimizing-move""

This reverts commit 4a37953377092ade93c15c72ad49cde4adaabd94.

Change-Id: Iae3bab9b104c1391070b329ef6a6a73b836189c8
diff --git a/build/Android.common_build.mk b/build/Android.common_build.mk
index acce68b..a443487 100644
--- a/build/Android.common_build.mk
+++ b/build/Android.common_build.mk
@@ -348,16 +348,6 @@
 ART_HOST_CFLAGS += -DART_DEFAULT_INSTRUCTION_SET_FEATURES=default $(art_host_cflags)
 ART_HOST_ASFLAGS += $(art_asflags)
 
-# Disable -Wpessimizing-move: triggered for art/runtime/base/variant_map.h:261
-# Adding this flag to art_clang_cflags doesn't work because -Wall gets added to
-# ART_HOST_CFLAGS (as a part of art_cflags) after
-# -Wno-pessimizing-move.  Instead, add the flag here to both
-# ART_TARGET_CLANG_CFLAGS and ART_HOST_CFLAGS
-ifeq ($(ART_HOST_CLANG),true)
-ART_HOST_CFLAGS += -Wno-pessimizing-move
-endif
-ART_TARGET_CLANG_CFLAGS += -Wno-pessimizing-move
-
 # The latest clang update trips over many of the files in art and never finishes
 # compiling for aarch64 with -O3 (or -O2). Drop back to -O1 while we investigate
 # to stop punishing the build server.