cmake: Use all pkgconf cflags for ImageMagick
Build fails with ImageMagick 7.1.1:
# error "you should set MAGICKCORE_HDRI_ENABLE"
The missing build flags are available from pkgconf --cflags-only-other
and as ${MAGICK_CFLAGS_OTHER}
in CMake. Add them to the build. This also fixes some warnings and is probably a good idea for all versions and flavors of Magick.
This patch is currently applied to the FreeBSD port, I'm the maintainer of that port.