Fix signal handler type mismatch.

Upstream bug: https://github.com/vapier/ncompress/pull/40

--- v5.0/compress.c	2021-06-17 15:14:20.000000000 +0100
+++ v5.0/compress.c	2025-07-06 02:33:26.412398934 +0100
@@ -174,10 +174,6 @@
 #	define	ARGS(a)				()
 #endif
 
-#ifndef SIG_TYPE
-#	define	SIG_TYPE	void (*)()
-#endif
-
 #if defined(AMIGA) || defined(DOS) || defined(MINGW) || defined(WINDOWS)
 #	define	chmod(pathname, mode) 0
 #	define	chown(pathname, owner, group) 0
@@ -539,6 +535,12 @@
 void  	prratio			ARGS((FILE *,long,long));
 void  	about			ARGS((void));
 
+void
+abort_handler(int dummy)
+{
+	abort_compress();
+}
+
 /*****************************************************************
  * TAG( main )
  *
@@ -590,14 +592,14 @@
 
 #ifdef SIGINT
 		if ((fgnd_flag = (signal(SIGINT, SIG_IGN)) != SIG_IGN))
-			signal(SIGINT, (SIG_TYPE)abort_compress);
+			signal(SIGINT, abort_handler);
 #endif
 
 #ifdef SIGTERM
-		signal(SIGTERM, (SIG_TYPE)abort_compress);
+		signal(SIGTERM, abort_handler);
 #endif
 #ifdef SIGHUP
-		signal(SIGHUP, (SIG_TYPE)abort_compress);
+		signal(SIGHUP, abort_handler);
 #endif
 
 #ifdef COMPATIBLE