Adding the readline CFLAGS to our own can define undesired symbols,
like for _GNU_SOURCE and _XOPEN_SOURCE.
We take extra precautions to remove _GNU_SOURCE
but a stray _XOPEN_SOURCE can break our build due to redefined symbols.
This change modifies the pkgconfig invocation
to only add the -I CFLAGS of the readline package,
which don't include symbol definitions
and spares us the trouble of having to remove them.
Adding the readline CFLAGS to our own can define undesired symbols, like for _GNU_SOURCE and _XOPEN_SOURCE. We take extra precautions to remove _GNU_SOURCE but a stray _XOPEN_SOURCE can break our build due to redefined symbols.
This change modifies the pkgconfig invocation to only add the -I CFLAGS of the readline package, which don't include symbol definitions and spares us the trouble of having to remove them.
Fixes #115