LibGfx: Remove support for the various "portable" image formats

These formats are not supported by other browsers.

Author: awesomekling

.gitattributes

@@ -5,7 +5,4 @@
 *.bmp binary
 *.gif binary
 *.jpg binary
-*.pbm binary
-*.pgm binary
 *.png binary
-*.ppm binary

AK/Debug.h.in

@@ -206,10 +206,6 @@
 #    cmakedefine01 PNG_DEBUG
 #endif
 
-#ifndef PORTABLE_IMAGE_LOADER_DEBUG
-#    cmakedefine01 PORTABLE_IMAGE_LOADER_DEBUG
-#endif
-
 #ifndef PROMISE_DEBUG
 #    cmakedefine01 PROMISE_DEBUG
 #endif