openh264: version check rejects same version

#1274 (closed) introduced a version check in gstopenh264plugin.c using memcmp which only registers the plugin when the return value is non-zero.

my understanding of memcmp is that it returns 0 when the two bits of memory are identical, so it has the effect of rejecting the case where the two version number sources (WelsGetCodecVersion and g_stCodecVersion) agree with each other.

Should the check be updated to only accept a zero return value?