acme: execute commands with / using shell

This allows commands in bin subdirectories.

R=rsc
CC=plan9port.codebot
https://codereview.appspot.com/13254044

src/cmd/acme/exec.c

diff --git a/src/cmd/acme/exec.c b/src/cmd/acme/exec.c
index ae6668c..59ae228 100644
--- a/src/cmd/acme/exec.c
+++ b/src/cmd/acme/exec.c
@@ -1479,7 +1479,7 @@
 			continue;
 		if(r < ' ')
 			goto Hard;
-		if(utfrune("#;&|^$=`'{}()<>[]*?^~`", r))
+		if(utfrune("#;&|^$=`'{}()<>[]*?^~`/", r))
 			goto Hard;
 		inarg = TRUE;
 	}