avcodec, avformat/ffjni: fix duplicate JNI symbols

Use SHLIBOBJS and STLIBOBJS in the Makefiles for avcodec and avformat,
and add a stub ffjni.c to libavformat, which allows the symbols to be
duplicated for shared builds but not static builds.

Signed-off-by: Leo Izen <leo.izen@gmail.com>
Signed-off-by: Matthieu Bouron <matthieu.bouron@gmail.com>

libavcodec/Makefile

@@ -1068,6 +1068,7 @@ STLIBOBJS-$(CONFIG_ISO_MEDIA)          += mpegaudiotabs.o
 STLIBOBJS-$(CONFIG_FLV_MUXER)          += mpeg4audio_sample_rates.o
 STLIBOBJS-$(CONFIG_HLS_DEMUXER)        += ac3_channel_layout_tab.o
 STLIBOBJS-$(CONFIG_IMAGE_JPEGXL_PIPE_DEMUXER) += jpegxl_parse.o
+STLIBOBJS-$(CONFIG_JNI)                += ffjni.o
 STLIBOBJS-$(CONFIG_JPEGXL_ANIM_DEMUXER)       += jpegxl_parse.o
 STLIBOBJS-$(CONFIG_MATROSKA_DEMUXER)   += mpeg4audio_sample_rates.o
 STLIBOBJS-$(CONFIG_MOV_DEMUXER)        += ac3_channel_layout_tab.o

libavformat/Makefile

@@ -728,6 +728,7 @@ SHLIBOBJS-$(CONFIG_ISO_MEDIA)            += mpegaudiotabs.o
 SHLIBOBJS-$(CONFIG_FLV_MUXER)            += mpeg4audio_sample_rates.o
 SHLIBOBJS-$(CONFIG_HLS_DEMUXER)          += ac3_channel_layout_tab.o
 SHLIBOBJS-$(CONFIG_IMAGE_JPEGXL_PIPE_DEMUXER)    += jpegxl_parse.o
+SHLIBOBJS-$(CONFIG_JNI)                  += ffjni.o
 SHLIBOBJS-$(CONFIG_JPEGXL_ANIM_DEMUXER)  += jpegxl_parse.o
 SHLIBOBJS-$(CONFIG_MATROSKA_DEMUXER)     += mpeg4audio_sample_rates.o
 SHLIBOBJS-$(CONFIG_MOV_DEMUXER)          += ac3_channel_layout_tab.o

libavformat/ffjni.c

@@ -0,0 +1,23 @@
+/*
+ * JNI utility functions - included stub
+ *
+ * Copyright (c) 2024 Leo Izen <leo.izen@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavcodec/ffjni.c"

libavformat/file.c

@@ -527,8 +527,8 @@ const URLProtocol ff_fd_protocol = {
 
 #if CONFIG_ANDROID_CONTENT_PROTOCOL
 #include <jni.h>
+#include "libavcodec/ffjni.h"
 #include "libavcodec/jni.h"
-#include "libavcodec/ffjni.c"
 
 typedef struct JFields {
     jclass uri_class;