Add LLMessageSystem::hasFast to avoid excessive mutex locks and string finds

indra/llmessage/message.cpp

@@ -3962,6 +3962,11 @@ BOOL	LLMessageSystem::has(const char *blockname) const
 	return getNumberOfBlocks(blockname) > 0;
 }
 
+BOOL	LLMessageSystem::hasFast(const char *blockname) const
+{
+	return getNumberOfBlocksFast(blockname) > 0;
+}
+
 S32	LLMessageSystem::getNumberOfBlocksFast(const char *blockname) const
 {
 	return mMessageReader->getNumberOfBlocks(blockname);

indra/llmessage/message.h

@@ -726,6 +726,7 @@ class LLMessageSystem : public LLMessageSenderInterface
 	void	sanityCheck();
 
 	BOOL	has(const char *blockname) const;
+	BOOL	hasFast(const char *blockname) const;
 	S32		getNumberOfBlocksFast(const char *blockname) const;
 	S32		getNumberOfBlocks(const char *blockname) const;
 	S32		getSizeFast(const char *blockname, const char *varname) const;