Limit buffer reset to only when it is necessary
Limit buffer reset to only when it is necessary

This commit adds conditions to reset pixel values in frame buffer,
so to limit the buffer reset to only when reset is necessary.

BUG=oss-fuzz:10204
BUG=oss-fuzz:10200
BUG=oss-fuzz:10209

Change-Id: I0cbece6b7c2c4db29314a59df5c27fa7682d3042

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom