expand - Fix dangling left square brackets in patterns

When there is an unmatched left square bracket in patterns, pmatch
will behave strangely and exhibit undefined behaviour.  This patch
(based on Harld van Dijk's original) fixes this by treating it as
a literal left square bracket.

Reported-by: Olof Johansson <olof@ethup.se>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

src/expand.c

@@ -1584,14 +1584,14 @@ pmatch(const char *pattern, const char *string)
 				p++;
 			}
 			found = 0;
-			chr = *q++;
+			chr = *q;
 			if (chr == '\0')
 				return 0;
 			c = *p++;
 			do {
 				if (!c) {
 					p = startp;
-					c = *p;
+					c = '[';
 					goto dft;
 				}
 				if (c == '[') {
@@ -1618,6 +1618,7 @@ pmatch(const char *pattern, const char *string)
 			} while ((c = *p++) != ']');
 			if (found == invert)
 				return 0;
+			q++;
 			break;
 		}
 dft:	        default: