adjust egrep value in var.mk

For some reason, some people have a think against `egrep`
and whine if you use that command.  To avoid this, EGREP
is set to `grep -E` instead.

var.mk

@@ -65,7 +65,7 @@ DIFF= diff
 DIG= dig
 DIRNAME= dirname
 ED= ed
-EGREP= egrep
+EGREP= grep -E
 ENV= env
 EQN= eqn
 ETAGS= etags