do not require installed libapt-pkg-dev for gtest

Git-Dch: Ignore

test/libapt/makefile

@@ -8,7 +8,7 @@ APT_DOMAIN=none
 include ../../buildlib/defaults.mak
 
 .PHONY: test
-ifeq (file-okay,$(shell $(CC) -M gtest_runner.cc >/dev/null 2>&1 && echo 'file-okay'))
+ifeq (file-okay,$(shell $(CC) -I $(BASE)/build/include -M gtest_runner.cc >/dev/null 2>&1 && echo 'file-okay'))
 test: $(BIN)/gtest$(BASENAME)
 	MALLOC_PERTURB_=21 MALLOC_CHECK_=2 LD_LIBRARY_PATH=$(LIB) $(BIN)/gtest$(BASENAME)
 
@@ -78,5 +78,6 @@ test:
 	@echo "APT uses Googles C++ testing framework for its unit tests"
 	@echo "On Debian systems this is available in the 'libgtest-dev' package."
 	@echo "Please install it before attempting to run the unit tests."
+	$(CC) -I $(BASE)/build/include -M gtest_runner.cc
 	exit 100
 endif