use snprintf(3) instead of sprintf(3)

Index: src/jit.c
--- src/jit.c.orig
+++ src/jit.c
@@ -1627,9 +1627,10 @@ static void call_native_consts( jit_ctx *ctx, void *na
 }
 
 static void on_jit_error( const char *msg, int_val line ) {
-	char buf[256];
+	size_t buflen = 256;
+	char buf[buflen];
 	int iline = (int)line;
-	sprintf(buf,"%s (line %d)",msg,iline);
+	snprintf(buf,buflen,"%s (line %d)",msg,iline);
 #ifdef HL_WIN_DESKTOP
 	MessageBoxA(NULL,buf,"JIT ERROR",MB_OK);
 #else
