Build gtest from source rather than using SDK-provided version

ports/glibc-compat/Makefile

Index: ports/glibc-compat/Makefile
diff --git a/ports/glibc-compat/Makefile b/ports/glibc-compat/Makefile
index 72fb15ef916d402cc81d2c7bc5ac2bb41201a999..1c2fb6c628b2d3f18eb6ed5083ad8d39d065f114 100644
--- a/ports/glibc-compat/Makefile
+++ b/ports/glibc-compat/Makefile
@@ -9,6 +9,7 @@ endif
 CFLAGS += -Wno-implicit-function-declaration
 CPPFLAGS += -Werror -Wno-unused-value -pthread
 CPPFLAGS += -DNACL_SDK_VERSION=$(NACL_SDK_VERSION)
+CPPFLAGS += -I$(GTEST_DIR)/include
 OUT := out
 SOURCES := \
   src/alarm.c \
@@ -59,30 +60,33 @@ CC_PREFIX =  @echo " CC  $@";
 AR_PREFIX =  @echo " AR  $@";
 endif
 
-
 ifeq ($(LIBC),newlib)
 LIB = $(OUT)/libglibc-compat.a
 CPPFLAGS += -Iinclude -Isrc -D_LIBC
 endif
 
+all: $(LIB) $(OUT)/glibc_compat_test
+
 $(OUT)/%.o : src/%.c
 	@mkdir -p $(OUT)
 	$(CC_PREFIX)$(CC) -o $@ -c $< $(CFLAGS) $(CPPFLAGS)
 
+$(OUT)/gtest-all.o : $(GTEST_DIR)/src/gtest-all.cc
+	@mkdir -p $(OUT)
+	$(CXX_PREFIX)$(CXX) -o $@ -c $< $(CXXFLAGS) $(CPPFLAGS) -I$(GTEST_DIR)
+
 $(OUT)/%.o : src/%.cc
 	@mkdir -p $(OUT)
 	$(CXX_PREFIX)$(CXX) -o $@ -c $< $(CXXFLAGS) $(CPPFLAGS)
 
-all: $(LIB) $(OUT)/glibc_compat_test
-
 $(OUT)/libglibc-compat.a: $(OBJS)
 	$(AR_PREFIX)$(AR) rcs $@ $^
 
-TEST_LIBS=$(LIB) -lgtest -lpthread
+TEST_LIBS=$(LIB) $(OUT)/gtest-all.o -lpthread
 
-$(OUT)/glibc_compat_test: $(OUT)/test.o $(LIB)
+$(OUT)/glibc_compat_test: $(OUT)/test.o $(OUT)/gtest-all.o $(LIB)
 	@mkdir -p $(OUT)
-	$(CXX_PREFIX)$(CXX) -o $@ $< -L$(OUT) $(LDFLAGS) $(TEST_LIBS)
+	$(CXX_PREFIX)$(CXX) -o $@ $^ -L$(OUT) $(LDFLAGS) -pthread
 
 test: $(OUT)/glibc_compat_test