Subzero: Use ccache for building, if available.
This is needed since we are now using an absolute (and non-standard) path to clang++.
BUG= none
R=jvoung@chromium.org
Review URL: https://codereview.chromium.org/567393007
diff --git a/Makefile.standalone b/Makefile.standalone
index 5bd0b95..9a8ff2a 100644
--- a/Makefile.standalone
+++ b/Makefile.standalone
@@ -51,7 +51,8 @@
# It's recommended that CXX matches the compiler you used to build LLVM itself.
OPTLEVEL := -O0
-CXX := $(CLANG_PATH)/clang++
+CCACHE := `command -v ccache`
+CXX := CCACHE_CPP2=yes $(CCACHE) $(CLANG_PATH)/clang++
CXXFLAGS := $(LLVM_CXXFLAGS) -Wall -Wextra -Werror -fno-rtti \
-fno-exceptions $(OPTLEVEL) -g $(HOST_FLAGS) \