set major version of shlibs to 0

WARNING: this will break existing dynamically linked binaries if they
exist. If you have any:
	. re-build world statically first if necessary
	. remove libraries from /lib and /usr/lib
	. then build world

This change:
	. avoids possible future dismay when interfacing other
	  systems' binaries; done until they are abi-compatible

Thanks to Antoine Leca for pointing this out.

lib/libelf/Makefile

@@ -63,7 +63,7 @@ CFLAGS+=        -I. -I${.CURDIR}
 SRCS+=		mmap.c
 CFLAGS+=	-DNO_MMAP_FILE
 
-SHLIB_MAJOR=	1
+SHLIB_MAJOR=	0
 
 WARNS?=	6