astro/accrete: Fix RUNTIME

Segmentation Fault occurs if program is executed in a directory without
write privileges.

Patch provided exits gracefully if *fp is NULL before fprintf's attempt
to write to non-existent file.

- Add LICENSE BSD3CLAUSE

PR:		268661
Reported by:	eylusion@gmail.com

astro/accrete/Makefile

@@ -1,5 +1,6 @@
 PORTNAME=	accrete
 PORTVERSION=	1.0
+PORTREVISION=	1
 CATEGORIES=	astro
 MASTER_SITES=	SF
 
@@ -7,6 +8,8 @@ MAINTAINER=	ports@FreeBSD.org
 COMMENT=	Physical simulation of solar system planet formation
 WWW=		https://sourceforge.net/projects/accrete/
 
+LICENSE=	BSD3CLAUSE
+
 MAKE_ARGS=	CC="${CC}" CFLAGS="${CFLAGS}" PREFIX=${STAGEDIR}${PREFIX} \
 		CDEBUG="" COPT=""
 PLIST_FILES=	bin/accrete

astro/accrete/files/patch-display.c

@@ -0,0 +1,14 @@
+--- display.c.orig	2022-12-31 01:22:36 UTC
++++ display.c
+@@ -8,6 +8,11 @@ display_system (void)
+ 
+      FILE *f;
+      f = fopen("New.System", "w");
++	 if (f == NULL)
++	 {
++	   perror("New.System");
++	   exit(1);
++	 }
+ 
+      fprintf(f,"                         SYSTEM  CHARACTERISTICS\n");
+      fprintf(f,"Mass of central star:          %6.3f solar masses\n", stellar_mass_ratio);