-CFLAGS='-Wno-narrowing -O2 -ggdb -fno-omit-frame-pointer' \
-CXXFLAGS='-Wno-narrowing -O2 -ggdb -fno-omit-frame-pointer' \
-WERROR_CFLAGS='-fpermissive'" \
+CFLAGS+=' -Wno-narrowing -O2 -g -fno-omit-frame-pointer' \
+CXXFLAGS+=' -Wno-narrowing -O2 -g -fno-omit-frame-pointer' \
+WERROR_CFLAGS+=' -fpermissive'" \