mingw: avoid a buffer overrun in needs_hiding()

When this function is passed a path with a trailing slash, it runs right
over the end of that path.

Let's fix this.

Co-authored-by: Alexandr Miloslavskiy <[email protected]>
Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

compat/mingw.c

@@ -591,6 +591,8 @@ static inline int needs_hiding(const char *path)
 			/* ignore trailing slashes */
 			if (*path)
 				basename = path;
+			else
+				break;
 		}
 
 	if (hide_dotfiles == HIDE_DOTFILES_TRUE)