Accept == as an alias of = which is a popular GNU extension.

This is intentionally undocumented for now since it's not part
of any standard.

MFC after:	1 month

bin/test/test.c

@@ -144,6 +144,7 @@ struct t_op {
 	{"-L",	FILSYM,	UNOP},
 	{"-S",	FILSOCK,UNOP},
 	{"=",	STREQ,	BINOP},
+	{"==",	STREQ,	BINOP},
 	{"!=",	STRNE,	BINOP},
 	{"<",	STRLT,	BINOP},
 	{">",	STRGT,	BINOP},

tools/regression/bin/test/regress.sh

@@ -52,12 +52,15 @@ t ()
 }
 
 count=0
-echo "1..94"
+echo "1..97"
 
 t 0 'b = b' 
+t 0 'b == b' 
 t 1 'b != b' 
 t 0 '\( b = b \)' 
+t 0 '\( b == b \)' 
 t 1 '! \( b = b \)' 
+t 1 '! \( b == b \)' 
 t 1 '! -f /etc/passwd'
 
 t 0 '-h = -h'