fix stdin input for file(1)

[Bryan Steele]

My latest commit broke support for stdin input, whoops.

ok?

Index: file.c
===================================================================
RCS file: /cvs/src/usr.bin/file/file.c,v
retrieving revision 1.62
diff -u -p -u -r1.62 file.c
--- file.c      28 Jun 2017 15:42:49 -0000      1.62
+++ file.c      28 Jun 2017 16:42:40 -0000
@@ -217,12 +217,16 @@ prepare_input(struct input_file *inf, co
 {
        int     fd, mode, error;
 
+       inf->path = path;
+
        if (strcmp(path, "-") == 0) {
                if (fstat(STDIN_FILENO, &inf->sb) == -1) {
                        inf->error = errno;
                        inf->fd = -1;
+                       return;
                }
                inf->fd = STDIN_FILENO;
+               return;
        }
 
        if (Lflag)
@@ -232,6 +236,7 @@ prepare_input(struct input_file *inf, co
        if (error == -1) {
                inf->error = errno;
                inf->fd = -1;
+               return;
        }
 
        /* We don't need them, so don't open directories or symlinks. */
@@ -245,7 +250,6 @@ prepare_input(struct input_file *inf, co
        if (S_ISLNK(mode))
                read_link(inf, path);
        inf->fd = fd;
-       inf->path = path;
 }
 
 static void