Teach gunzip that .tbz and .tbz2 uncompress to .tar, in a manner similar to

its existing understanding that .tgz uncompresses to .tar.

MFC after:	3 days
PR:		121519
Submitted by:	Ighighi <ighighi at gmail.com>

usr.bin/gzip/gzip.c

@@ -133,6 +133,8 @@ static suffixes_t suffixes[] = {
 	SUFFIX(".tgz",		".tar"),
 #ifndef NO_BZIP2_SUPPORT
 	SUFFIX(BZ2_SUFFIX,	""),
+	SUFFIX(".tbz",		".tar"),
+	SUFFIX(".tbz2",		".tar"),
 #endif
 #ifndef NO_COMPRESS_SUPPORT
 	SUFFIX(Z_SUFFIX,	""),