Speed up of particular inefficient part related to motions.

For these standard motions, the viewer likes to very frequently
flood-call startMotion/stopMotion sometimes, which at the very
least needs a LLUUID lookup in a std::map. In particular, this
is done for two of them for every avatar in the sim every frame.
This code makes it possible to test if that makes sense by
merely doing a bit test.

Conflicts:
	indra/llcharacter/llkeyframemotion.h

indra/llcharacter/llkeyframemotion.cpp

@@ -468,7 +468,7 @@ LLKeyframeMotion::~LLKeyframeMotion()
 //-----------------------------------------------------------------------------
 // create()
 //-----------------------------------------------------------------------------
-LLMotion *LLKeyframeMotion::create(const LLUUID &id)
+LLMotion* LLKeyframeMotion::create(LLUUID const& id, LLMotionController&)
 {
 	return new LLKeyframeMotion(id);
 }