consistently use *_CFLAGS, AM_CPPFLAGS and CPPFLAGS
consistently use *_CFLAGS, AM_CPPFLAGS and CPPFLAGS

pestophagous/unofficial_scratchpad_git-cvsimport_libexif,pestophagous/unofficial_scratchpad_git-cvsimport_libexif,pestophagous/unofficial_scratchpad_git-cvsimport_libexif