Fix more typos in comments and documentation

* alloc.c: Fix typo ("overflow").
* configure.ac: Fix typo ("optimization").
* doc/README.amiga: Fix typos ("also", "specific", "unnecessary").
* doc/README.cords: Fix typos ("descendants", "highlighted").
* ChangeLog: Fix typos ("[un]collectible").
* README.md: Likewise.
* dbg_mlc.c: Likewise.
* doc/README.hp: Likewise.
* doc/README.linux: Likewise.
* doc/gcdescr.html: Likewise.
* doc/gcinterface.html: Likewise.
* include/gc_mark.h: Likewise.
* include/gc_pthread_redirects.h: Likewise.
* include/new_gc_alloc.h: Likewise.
* include/private/dbg_mlc.h: Likewise.
* include/private/gc_pmark.h: Likewise.
* include/private/gc_priv.h: Likewise.
* new_hblk.c: Likewise.
* ChangeLog: Fix typo ("multi-threaded").
* cord/cordxtra.c: Likewise.
* doc/debugging.html: Likewise.
* doc/gcinterface.html: Likewise.
* doc/leak.html: Likewise.
* doc/overview.html: Likewise.
* doc/simple_example.html: Likewise.
* include/gc_mark.h: Likewise.
* include/private/gc_priv.h: Likewise.
* os_dep.c: Likewise.
* ptr_chck.c: Likewise.
* README.md: Fix typo ("pointer-free").
* allchblk.c: Likewise.
* doc/debugging.html: Likewise.
* doc/gcdescr.html: Likewise.

1 files changed, 1 insertions, 1 deletions

diff --git a/ptr_chck.c b/ptr_chck.c
index 308bd531..011b27ef 100644
--- a/ptr_chck.c
+++ b/ptr_chck.c
@@ -183,7 +183,7 @@ void (GC_CALLBACK *GC_is_visible_print_proc)(void * p) =
 /* in hard cases.  (This is intended for debugging use with             */
 /* untyped allocations.  The idea is that it should be possible, though */
 /* slow, to add such a call to all indirect pointer stores.)            */
-/* Currently useless for multithreaded worlds.                          */
+/* Currently useless for the multi-threaded worlds.                     */
 GC_API void * GC_CALL GC_is_visible(void *p)
 {
     hdr *hhdr;