lavfi/vf_srcnn: use avio_check instead of access

The filter uses avio for file access already, and avio_check is
portable.

Fixes trac #7192.

configure

@@ -3389,7 +3389,7 @@ spectrumsynth_filter_deps="avcodec"
 spectrumsynth_filter_select="fft"
 spp_filter_deps="gpl avcodec"
 spp_filter_select="fft idctdsp fdctdsp me_cmp pixblockdsp"
-srcnn_filter_deps="access avformat"
+srcnn_filter_deps="avformat"
 stereo3d_filter_deps="gpl"
 subtitles_filter_deps="avformat avcodec libass"
 super2xsai_filter_deps="gpl"

libavfilter/vf_srcnn.c

@@ -28,9 +28,6 @@
 #include "formats.h"
 #include "internal.h"
 #include "libavutil/opt.h"
-#if HAVE_UNISTD_H
-#include <unistd.h>
-#endif
 #include "vf_srcnn.h"
 #include "libavformat/avio.h"
 
@@ -145,7 +142,7 @@ static av_cold int init(AVFilterContext* context)
         srcnn_context->conv3.size = 5;
         CHECK_ALLOCATION(allocate_copy_conv_data(&srcnn_context->conv3, conv3_kernel, conv3_biases), )
     }
-    else if (access(srcnn_context->config_file_path, R_OK) != -1){
+    else if (avio_check(srcnn_context->config_file_path, AVIO_FLAG_READ) > 0){
         if (avio_open(&config_file_context, srcnn_context->config_file_path, AVIO_FLAG_READ) < 0){
             av_log(context, AV_LOG_ERROR, "failed to open configuration file\n");
             return AVERROR(EIO);