* 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/include/sys/cygwin.h

@@ -86,7 +86,8 @@ typedef enum
     CW_ARGV,
     CW_ENVP,
     CW_DEBUG_SELF,
-    CW_SYNC_WINENV
+    CW_SYNC_WINENV,
+    CW_CYGTLS_PADSIZE
   } cygwin_getinfo_types;
 
 #define CW_NEXTPID	0x80000000	/* or with pid to get next one */