Don't use sigatomic before current task is available (#58320)

Author: gbaraldi

src/staticdata.c

@@ -3593,8 +3593,6 @@ JL_DLLEXPORT jl_image_buf_t jl_preload_sysimg(const char *fname)
             jl_errorf("System image file \"%s\" not found.", fname);
         ios_bufmode(&f, bm_none);
 
-        JL_SIGATOMIC_BEGIN();
-
         ios_seek_end(&f);
         size_t len = ios_pos(&f);
         char *sysimg = (char*)jl_gc_perm_alloc(len, 0, 64, 0);
@@ -3605,8 +3603,6 @@ JL_DLLEXPORT jl_image_buf_t jl_preload_sysimg(const char *fname)
 
         ios_close(&f);
 
-        JL_SIGATOMIC_END();
-
         jl_sysimage_buf = (jl_image_buf_t) {
             .kind = JL_IMAGE_KIND_JI,
             .pointers = NULL,