Makefile: use $PKGCONFIG, use += and ?= BSD extensions

Allows to use cross-compilation for ${triple}-pkg-config on systems
like Exherbo without special handling.

The BSD extensions += and ?= for variable extension is used to avoid having
to explicitely pass a list of variables to make, thus making build recipies
simpler.
Only issue is when CC is unset, you will get CC=c99, which doesn't works as c11
is used. Consider doing something like the following in your build recipes:

	make CC=${CC:-cc}

Reported-by: danyspin97

0 files changed, 0 insertions, 0 deletions