* cygtls.cc (_cygtls::call): Call call2 using _my_tls.

(_cygtls::init_exception_handler): Always replace existing exception handler
with cygwin exception handler.
* cygtls.h (_cygtls::call2): Remove static designation.
* dcrto.cc (dll_crt0_1): Define in a way that allows calling via _cygtls::call.
(_initialize_main_tls): Delete.
(_dll_crt0): Call dll_crt0_1 via cygtls::call.  Set _main_tls here.
* external.cc (cygwin_internal): Implement CW_CYGTLS_PADSIZE.
* include/sys/cygwin.h (CW_CYGTLS_PADSIZE): Define.
* tlsoffsets.h: Regenerate.

winsup/cygwin/external.cc

@@ -348,6 +348,8 @@ cygwin_internal (cygwin_getinfo_types t, ...)
       case CW_SYNC_WINENV:
 	sync_winenv ();
 	return 0;
+      case CW_CYGTLS_PADSIZE:
+	return CYGTLS_PADSIZE;
       default:
 	break;
     }