SPDX-License-Identifier: GPL-3.0-or-later

Fix SIGRETURN for Linux builds when VOID_SIGHANDLER probe is inaccurate.

On modern Linux toolchains, signal handlers return void. If VOID_SIGHANDLER
is not defined during configure probing, SIGRETURN expands to return(n),
which fails in void handlers (e.g. eval.c: alrm_catcher).

--- bash-4.4/sig.h
+++ bash-4.4/sig.h
@@ -34,7 +34,7 @@
 #define sighandler RETSIGTYPE
 typedef RETSIGTYPE SigHandler __P((int));
 
-#if defined (VOID_SIGHANDLER)
+#if defined (VOID_SIGHANDLER) || defined (__linux__)
 #  define SIGRETURN(n)	return
 #else
 #  define SIGRETURN(n)	return(n)