Rip out old workarounds, hacks and macros for newer C++ features not being supported back in the day.

Adds LL_COMPILE_TIME_MESSAGE support to Linux.

llfinite -> std::isfinite
llisnan -> std::isnan
vector_shrink_to_fit -> vector.shrink_to_fit

indra/newview/llviewerobject.cpp

@@ -1822,7 +1822,7 @@ U32 LLViewerObject::processUpdateMessage(LLMessageSystem *mesgsys,
 		
 		LLVector3 diff = new_pos_parent - test_pos_parent ;
 		F32 mag_sqr = diff.magVecSquared() ;
-		if(llfinite(mag_sqr)) 
+		if(std::isfinite(mag_sqr))
 		{
 			setPositionParent(new_pos_parent);
 		}