Remove "Supported codecs:" lines from aomcx.h
Remove "Supported codecs:" lines from aomcx.h

There is currently only one codec supported by this library.

BUG=aomedia:5

Change-Id: Ic83f09b8ca783fcdf0117d338858f3fcee55e038

luctrudeau/aom,GrokImageCompression/aom,GrokImageCompression/aom,luctrudeau/aom,smarter/aom,smarter/aom,smarter/aom,GrokImageCompression/aom,luctrudeau/aom,GrokImageCompression/aom,GrokImageCompression/aom,luctrudeau/aom,luctrudeau/aom,GrokImageCompression/aom,luctrudeau/aom,smarter/aom,smarter/aom,smarter/aom