avformat/img2enc: disable atomic file creation by default

Currently it is broken when explicitly using the file protocol, it uses an
insecure temporary file name, and in commit b4431c80 disabling the option by
default was already considered. Also it is not very consistent to have such an
option for one particular muxer.
Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/img2enc.c

@@ -73,9 +73,6 @@ static int write_header(AVFormatContext *s)
                              && desc->nb_components >= 3;
     }
 
-    img->use_rename = img->use_rename < 0 ? proto && !strcmp(proto, "file")
-                                          : img->use_rename;
-
     return 0;
 }
 
@@ -208,7 +205,7 @@ static const AVOption muxoptions[] = {
     { "update",       "continuously overwrite one file", OFFSET(update),  AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0,       1, ENC },
     { "start_number", "set first number in the sequence", OFFSET(img_number), AV_OPT_TYPE_INT,  { .i64 = 1 }, 0, INT_MAX, ENC },
     { "strftime",     "use strftime for filename", OFFSET(use_strftime),  AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, ENC },
-    { "atomic_writing", "write files atomically (using temporary files and renames)", OFFSET(use_rename), AV_OPT_TYPE_BOOL, { .i64 = -1 }, -1, 1, ENC },
+    { "atomic_writing", "write files atomically (using temporary files and renames)", OFFSET(use_rename), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, ENC },
     { NULL },
 };