Tune SAFE_FREE

On my platform (Fedora 28 x86-64, AMD Phenom II X4 910e) this sped
up a SAFE_FREE-using microbenchmark (string-distance "abc" "abc")
by about 18%, and shrank the Emacs text size by about 0.1%.
* src/callint.c (Fcall_interactively):
* src/callproc.c (call_process):
* src/doc.c (get_doc_string, Fsnarf_documentation):
* src/editfns.c (Freplace_buffer_contents):
* src/emacs-module.c (funcall_module):
* src/eval.c (Flet):
* src/process.c (Fmake_process):
* src/term.c (tty_menu_show):
* src/xdisp.c (safe__call):
* src/xmenu.c (x_menu_show):
Use SAFE_FREE_UNBIND_TO.
* src/data.c (wrong_choice): No need to call SAFE_FREE here.
* src/lisp.h (USE_SAFE_ALLOCA):
* src/regex.c (REGEX_USE_SAFE_ALLOCA):
Do not declare sa_must_free local; no longer needed.
All uses removed.
(SAFE_FREE): Rewrite in terms of safe_free.
(safe_free): New function, optimized to use xfree.
(SAFE_FREE_UNBIND_TO): New macro.
(safe_free_unbind_to): New function.

1 files changed, 1 insertions, 2 deletions

diff --git a/src/eval.c b/src/eval.c
index 952a0ec4b46..9e0fabdcfba 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -981,8 +981,7 @@ usage: (let VARLIST BODY...)  */)
     specbind (Qinternal_interpreter_environment, lexenv);
 
   elt = Fprogn (XCDR (args));
-  SAFE_FREE ();
-  return unbind_to (count, elt);
+  return SAFE_FREE_UNBIND_TO (count, elt);
 }
 
 DEFUN ("while", Fwhile, Swhile, 1, UNEVALLED, 0,