Rename thread_init() in libavcodec and libavfilter as library_thread_init().

The aix header sys/thread.h contains a definition for thread_init().

libavcodec/pthread.c

@@ -249,7 +249,7 @@ static int avcodec_thread_execute2(AVCodecContext *avctx, action_func2* func2, v
     return avcodec_thread_execute(avctx, NULL, arg, ret, job_count, 0);
 }
 
-static int thread_init(AVCodecContext *avctx)
+static int avcodec_thread_init(AVCodecContext *avctx)
 {
     int i;
     ThreadContext *c;
@@ -1103,7 +1103,7 @@ int ff_thread_init(AVCodecContext *avctx)
     validate_thread_parameters(avctx);
 
     if (avctx->active_thread_type&FF_THREAD_SLICE)
-        return thread_init(avctx);
+        return avcodec_thread_init(avctx);
     else if (avctx->active_thread_type&FF_THREAD_FRAME)
         return frame_thread_init(avctx);
 

libavfilter/pthread.c

@@ -146,7 +146,7 @@ static int thread_execute(AVFilterContext *ctx, action_func *func,
     return 0;
 }
 
-static int thread_init(ThreadContext *c, int nb_threads)
+static int avfilter_thread_init(ThreadContext *c, int nb_threads)
 {
     int i, ret;
 
@@ -208,7 +208,7 @@ int ff_graph_thread_init(AVFilterGraph *graph)
     if (!graph->internal->thread)
         return AVERROR(ENOMEM);
 
-    ret = thread_init(graph->internal->thread, graph->nb_threads);
+    ret = avfilter_thread_init(graph->internal->thread, graph->nb_threads);
     if (ret <= 1) {
         av_freep(&graph->internal->thread);
         graph->thread_type = 0;