[truetype] Fix for the family name shorter than 8 characters.

* src/truetype/ttobjs.c (tt_skip_pdffont_random_tag):
If the family name to be checked is shorter than 8 characters,
do not check its syntax.

src/truetype/ttobjs.c

@@ -156,7 +156,7 @@
     unsigned int  i;
 
 
-    if ( name[6] != '+' )
+    if ( ft_strlen( name ) < 8 || name[6] != '+' )
       return name;
 
     for ( i = 0; i < 6; i++ )