New comment by avoidr on void-packages repository

https://github.com/void-linux/void-packages/pull/19928#issuecomment-599239766

Comment:
I was confused about the meaning of `-e` in make. I thought it is necessary for it to use environment variables, but it is only about precedence. The CFLAGS didn't get used because `-e` overrode them. `make` worked correctly without `-e`, using the env var and having flags appended from the Makefile.

The actual problem I had was being unable to set CC by environment, because the Makefile already set CC explicitly. The fix was to set CC conditionally based on whether it has its default value, or it has been redefined — basically falling back to a default if not otherwise specified.