path: Fix Glob when it finds a file in directory position.

When searching a list of directories, the files which match
the pattern are accumulated in a slice.  If the glob has a
wildcard for the directory, and the wildcard matches a file
rather than a directory, then the files found so far are
discarded.  E.g., path.Glob("*/x") in a directory which
contains both files and subdirectories.  This patch avoids
discarding matches found so far when a file is found.

R=r
CC=bsiegert, golang-dev
https://golang.org/cl/3015042

src/pkg/path/match.go

@@ -240,9 +240,13 @@ func Glob(pattern string) (matches []string) {
 // glob searches for files matching pattern in the directory dir
 // and appends them to matches.
 func glob(dir, pattern string, matches []string) []string {
-	if fi, err := os.Stat(dir); err != nil || !fi.IsDirectory() {
+	fi, err := os.Stat(dir)
+	if err != nil {
 		return nil
 	}
+	if !fi.IsDirectory() {
+		return matches
+	}
 	d, err := os.Open(dir, os.O_RDONLY, 0666)
 	if err != nil {
 		return nil