change underscores to hyphens in announcement of new PNG defines.
change underscores to hyphens in announcement of new PNG defines.


git-svn-id: 7f11a4e55de7d4642c7675696f15857479c93c9d@4673 aa41f4f7-0bf4-0310-aa73-e5a19afd5a74

svn2github/ImageMagick,brightinteractive/debian-imagemagick,brightinteractive/debian-imagemagick,svn2github/ImageMagick,Distrotech/ImageMagick,brightinteractive/debian-imagemagick,brightinteractive/debian-imagemagick,Distrotech/ImageMagick,svn2github/ImageMagick,Distrotech/ImageMagick,svn2github/ImageMagick,Distrotech/ImageMagick