Fix subtle bug in ReadPipeImpl: wouldn't tolerate multiple instances.

That is, trying to instantiate a ReadPipeImpl while another already existed
would throw an LLEventPump::DupPumpName exception. Fortunately this behavior
is easily bypassed.

indra/llcommon/llprocess.cpp

@@ -209,7 +209,7 @@ class ReadPipeImpl: public LLProcess::ReadPipe
 		mPipe(pipe),
 		// Essential to initialize our std::istream with our special streambuf!
 		mStream(&mStreambuf),
-		mPump("ReadPipe"),
+		mPump("ReadPipe", true),    // tweak name as needed to avoid collisions
 		// use funky syntax to call max() to avoid blighted max() macros
 		mLimit(npos)
 	{