-Screwed around with SSE2.

-Added ReleaseSSE2 as a build target.
-LL_VECTORIZE is silly and breaks things...
-Small little tweaks.

I have not tested if the cmake alterations work under linux and darwin. Hollar if broken.

indra/llmessage/lltemplatemessagebuilder.cpp

@@ -326,7 +326,7 @@ void LLTemplateMessageBuilder::addData(const char *varname, const void *data, EM
 			       << "(" << size << ").  Clamping size and truncating data." << llendl;
 			size = 255;
 			char *truncate = (char *)data;
-			truncate[255] = 0;
+			truncate[254] = 0; // array size is 255 but the last element index is 254
 		}
 
 		// no correct size for MVT_VARIABLE, instead we need to tell how many bytes the size will be encoded as
@@ -737,10 +737,14 @@ static S32 buildBlock(U8* buffer, S32 buffer_size, const LLMessageBlock* templat
 		}
 
 		--block_count;
-		++block_iter;
+		
 		if (block_iter != message_data->mMemberBlocks.end())
 		{
-			mbci = block_iter->second;
+			++block_iter;
+			if (block_iter != message_data->mMemberBlocks.end())
+			{
+				mbci = block_iter->second;
+			}
 		}
 	}