GH408 follow-on: update buflen

Some builds break, as documented in:
  https://github.com/openssl/openssl/pull/408#issuecomment-142971427
This fixes it.
Signed-off-by: NRich Salz <rsalz@akamai.com>
Reviewed-by: NTim Hudson <tjh@openssl.org>

apps/rehash.c

@@ -74,6 +74,9 @@
 # include <openssl/x509.h>
 
 
+# ifndef NAME_MAX
+#  define NAME_MAX 255
+# endif
 # define MAX_COLLISIONS  256
 
 typedef struct hentry_st {
@@ -319,7 +322,8 @@ static int do_dir(const char *dirname, enum Hash h)
     }
     buflen = strlen(dirname);
     pathsep = (buflen && dirname[buflen - 1] == '/') ? "" : "/";
-    buf = app_malloc(PATH_MAX, "filename buffer");
+    buflen += NAME_MAX + 1 + 1;
+    buf = app_malloc(buflen, "filename buffer");
 
     if (verbose)
         BIO_printf(bio_out, "Doing %s\n", dirname);