Include of gtest_prod.h only building unittests

Change-Id: I605ba14fa7e205158aef671c98938b911362b5b6
Reviewed-on: https://weave-review.googlesource.com/2329
Reviewed-by: Jacob Marble <jacobmarble@google.com>
Reviewed-by: Alex Vakulenko <avakulenko@google.com>
diff --git a/Makefile b/Makefile
index 4ea625f..de69f40 100644
--- a/Makefile
+++ b/Makefile
@@ -71,6 +71,10 @@
 OBJFILES = $(shell find out/$(BUILD_MODE)/ -type f -name '*.o')
 -include $(OBJFILES:.o=.d)
 
+DEFS_TEST := \
+	$(DEFS_$(BUILD_MODE)) \
+	-DHAS_GTEST=1
+
 ###
 # libweave.so
 
@@ -85,7 +89,7 @@
 weave_obj_files := $(WEAVE_SRC_FILES:%.cc=out/$(BUILD_MODE)/%.o)
 
 # TODO(jacobmarble): There are too many gtest/gmock deps in non-test targets. Fix.
-$(weave_obj_files) : out/$(BUILD_MODE)/%.o : %.cc third_party/include/gtest/gtest.h
+$(weave_obj_files) : out/$(BUILD_MODE)/%.o : %.cc
 	mkdir -p $(dir $@)
 	$(CXX) $(DEFS_$(BUILD_MODE)) $(INCLUDES) $(CFLAGS) $(CFLAGS_$(BUILD_MODE)) $(CFLAGS_CC) -c -o $@ $<
 
@@ -93,7 +97,7 @@
 	rm -f $@
 	$(AR) crsT $@ $^
 
-all : out/$(BUILD_MODE)/libweave.so out/$(BUILD_MODE)/libweave_exports_testrunner out/$(BUILD_MODE)/libweave_testrunner all-examples
+all : out/$(BUILD_MODE)/libweave.so all-examples out/$(BUILD_MODE)/libweave_exports_testrunner out/$(BUILD_MODE)/libweave_testrunner
 
 clean :
 	rm -rf out