pkg-config --cflags behaves different than freedesktops pkg-config #41

I am not sure if this is a bug really, but I am reporting it here for the record as it has influence on how some packages are built.

With freedesktop's pkg-config there is a single space returned:

$ echo "flags='$(pkg-config --cflags lua)'"
flags=' '

With pkgconf that space is missing.

rrdtool has a pretty stupid configure script:

   if test "$LUA_CFLAGS" = ""; then
      ...

which will result in a different result than freedesktop's pkg-config.

I am not sure how close you want follow freedesktops pkg-config.