Update comments warning about GC-resistant C programming

* src/eval.c: Remove an outdated comment about protection from GC.
* src/buffer.h:
* src/lisp.h: Add warnings about using 'char *' pointers to text
of Lisp strings and buffer text in code that could GC.  Reported by
Po Lu <luangruo@yahoo.com>

1 files changed, 0 insertions, 3 deletions

diff --git a/src/eval.c b/src/eval.c
index 76fe671b6dd..2bb7cfe6002 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -364,9 +364,6 @@ do_debug_on_call (Lisp_Object code, ptrdiff_t count)
   call_debugger (list1 (code));
 }
 
-/* NOTE!!! Every function that can call EVAL must protect its args
-   and temporaries from garbage collection while it needs them.
-   The definition of `For' shows what you have to do.  */
 
 DEFUN ("or", For, Sor, 0, UNEVALLED, 0,
        doc: /* Eval args until one of them yields non-nil, then return that value.