Move shared headers in common/include

Headers that will be shared between old includes and NetBSD-like includes
are moved into common/include tree. They are still copied in /usr/include
in 'make includes', so compilation and programs aren't be affected.

include/minix/debug.h

@@ -1,22 +0,0 @@
-#ifndef _MINIX_DEBUG_H
-#define _MINIX_DEBUG_H 1
-
-/* For reminders of things to be fixed. */
-#define FIXME(str) { static int fixme_warned = 0; \
-	if(!fixme_warned) { \
-		printf("FIXME: %s:%d: %s\n", __FILE__, __LINE__, str);\
-		fixme_warned = 1; \
-	} \
-}
-
-#define NOT_REACHABLE	do {						\
-	panic("NOT_REACHABLE at %s:%d", __FILE__, __LINE__);	\
-	for(;;);							\
-} while(0)
-
-#define NOT_IMPLEMENTED do {	\
-		panic("NOT_IMPLEMENTED at %s:%d", __FILE__, __LINE__); \
-} while(0)
-
-#endif /* _MINIX_DEBUG_H */
-