* cygheap.h (init_cygheap): Play more vfork shell games and move ctty_on_hold

and open_fhs_on_hold (back) here.
* dcrt0.cc (_dll_crt0): Just set impure_ptr_ptr here and let later
initialization deal with tls.
* dtable.cc (dtable::vfork_child_fixup): Move ctty considerations here.
(dtable:vfork_parent_restore): And here.
* fork.cc (vfork): Reflect change to ctty handling.
* perthread.h (vfork_save::fhctty): Eliminate.
* cygwin.din: Make more exports NOSIGFE that will never be interrupted by a
signal.
* init.cc (dll_entry): Set stackptr to NULL to catch problems earlier.

winsup/cygwin/cygtls.h

@@ -28,6 +28,8 @@ details. */
 # define UNLEN 256
 #endif
 
+#define TLS_STACK_SIZE 1024
+
 #pragma pack(push,4)
 struct _local_storage
 {
@@ -107,7 +109,7 @@ struct _threadinfo
   struct _threadinfo *prev, *next;
   __stack_t *stackptr;
   int sig;
-  __stack_t stack[1024];
+  __stack_t stack[TLS_STACK_SIZE];
 
   /*gentls_offsets*/
   static CRITICAL_SECTION protect_linked_list;