mpeg2vidcodec: fix implicit declarations

Closes: https://trac.macports.org/ticket/72127

multimedia/mpeg2vidcodec/Portfile

@@ -22,7 +22,8 @@ master_sites            http://www.mpeg.org/pub_ftp/mpeg/mssg/ \
 distname                mpeg2
 distfiles               ${name}_v12${extract.suffix}
 checksums               md5 4a66565979be0818bd8a41d948943451
-platforms               darwin
+
+patchfiles              implicit.patch
 
 variant x11 {
     depends_lib         port:xorg-libXext

multimedia/mpeg2vidcodec/files/implicit.patch

@@ -0,0 +1,63 @@
+--- src/mpeg2dec/mpeg2dec.c.orig	1996-07-20 08:27:38
++++ src/mpeg2dec/mpeg2dec.c	2025-03-03 01:27:30
+@@ -32,6 +32,7 @@
+ #include <stdlib.h>
+ #include <ctype.h>
+ #include <fcntl.h>
++#include <unistd.h>
+
+ #define GLOBAL
+ #include "config.h"
+--- src/mpeg2enc/readpic.c.orig	1996-07-20 08:49:30
++++ src/mpeg2enc/readpic.c	2025-03-03 01:30:02
+@@ -147,6 +147,8 @@ unsigned char *frame[];
+
+   fclose(fd);
+ }
++
++int pbm_getint(FILE* file);
+
+ static void read_ppm(fname,frame)
+ char *fname;
+--- src/mpeg2dec/getbits.c.orig	1995-12-31 13:59:54
++++ src/mpeg2dec/getbits.c	2025-03-03 01:33:54
+@@ -34,6 +34,7 @@
+
+ #include <stdio.h>
+ #include <stdlib.h>
++#include <unistd.h>
+
+ #include "config.h"
+ #include "global.h"
+--- src/mpeg2dec/store.c.orig	1996-01-09 22:03:42
++++ src/mpeg2dec/store.c	2025-03-03 01:36:15
+@@ -29,7 +29,9 @@
+
+ #include <stdio.h>
+ #include <stdlib.h>
++#include <string.h>
+ #include <fcntl.h>
++#include <unistd.h>
+
+ #include "config.h"
+ #include "global.h"
+--- src/mpeg2dec/spatscal.c.orig	1996-07-20 08:31:36
++++ src/mpeg2dec/spatscal.c	2025-03-03 01:37:56
+@@ -1,5 +1,7 @@
+
+ #include <stdio.h>
++#include <stdlib.h>
++#include <string.h>
+ #include "config.h"
+ #include "global.h"
+
+--- src/mpeg2dec/subspic.c.orig	1996-07-20 07:44:49
++++ src/mpeg2dec/subspic.c	2025-03-03 01:39:57
+@@ -31,6 +31,7 @@
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <fcntl.h>
++#include <unistd.h>
+
+ #include "config.h"
+ #include "global.h"