Snippets for pth 2.0.7 from Nix aarch64-darwin

Sourced from https://hydra.nixos.org/log/zy5v6bmmz7vnswji2g3a9zdbn53vh61g-pth-2.0.7.drv.

• pth_high.c:773:31: warning: while loop has empty body [-Wempty-body]
    773 |            && errno == EINTR) ;
        |                               ^
  

• pth_high.c:947:31: warning: while loop has empty body [-Wempty-body]
    947 |            && errno == EINTR) ;
        |                               ^
  

• pth_high.c:1376:31: warning: while loop has empty body [-Wempty-body]
   1376 |            && errno == EINTR) ;
        |                               ^
  

• test_uctx.c:45:22: warning: cast to smaller integer type 'int' from 'void *' [-Wvoid-pointer-to-int-cast]
     45 |     volatile int n = (int)ctx;
        |                      ^~~~~~~~
  

• test_uctx.c:71:61: warning: cast to 'void *' from smaller integer type 'int' [-Wint-to-void-pointer-cast]
     71 |         pth_uctx_make(uctx[i], NULL, 32*1024, NULL, worker, (void *)i, uctx[0]);
        |                                                             ^~~~~~~~~