Revert "make bool m_echo static" - I suspect this to be defined by spec

This reverts commit 3cb133d27d.

src/hci/mucurses/kb.c

 		0   : non-blocking read
 		> 0 : timed blocking read
 	     */
-static bool m_echo;
+bool m_echo;
 bool m_cbreak;
 
 #if 0