Throughout, (mainly in fhandler*) fix remaining gcc 4.7 mismatch

warnings between regparm definitions and declarations.
* smallprint.cc (__small_vswprintf): Conditionalize declaration and
setting of l_opt for only x86_64.
* spawn.cc (child_info_spawn::worker): Remove unused 'pid' variable.
* thread.cc (verifyable_object_isvalid): Temporarily define as
non-inline with gcc 4.7+, regardless of target.

winsup/cygwin/window.cc

@@ -26,7 +26,7 @@ wininfo NO_COPY winmsg;
 
 muto NO_COPY wininfo::_lock;
 
-int __stdcall
+int __reg3
 wininfo::process (HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
 {
 #ifndef NOSTRACE
@@ -57,7 +57,7 @@ process_window_events (HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
 }
 
 /* Handle windows events.  Inherits ownership of the wininfo lock */
-DWORD WINAPI
+DWORD __reg1 WINAPI
 wininfo::winthread ()
 {
   MSG msg;