osgdb_pngd.dlll -> osgdb_pngd.dll for Debug build, disable 64-bit portability warnings for Release build
osgdb_pngd.dlll -> osgdb_pngd.dll for Debug build, disable 64-bit portability warnings for Release build

git-svn-id: 7c9ea37791cd259b24cbb3dc83a0e12673e3c8a9@15526 08b3d480-bf2c-0410-a26f-811ee3361c24

BZFlag-Dev/bzworkbench,BZFlag-Dev/bzworkbench,BZFlag-Dev/bzworkbench