tor: fix build

Monotonic timer test expects sleep(200ms) to take at most 1s. On
loaded systems like hydra, it's possible for such a test to take
longer than 1 second.

Tests expecting sleep(200ms) to take at least 175ms weren't removed,
because load shouldn't cause sleep to be shorter.

pkgs/tools/security/tor/default.nix

@@ -28,6 +28,8 @@ stdenv.mkDerivation rec {
   buildInputs = [ libevent openssl zlib lzma zstd scrypt ] ++
     stdenv.lib.optionals stdenv.isLinux [ libseccomp systemd libcap ];
 
+  patches = [ ./disable-monotonic-timer-tests.patch ];
+
   NIX_CFLAGS_LINK = stdenv.lib.optionalString stdenv.cc.isGNU "-lgcc_s";
 
   postPatch = ''
@@ -39,7 +41,6 @@ stdenv.mkDerivation rec {
   '';
 
   enableParallelBuilding = true;
-  enableParallelChecking = false; # 4 tests fail randomly
 
   doCheck = true;
 

pkgs/tools/security/tor/disable-monotonic-timer-tests.patch

@@ -0,0 +1,26 @@
+diff --git a/src/test/test_util.c b/src/test/test_util.c
+index 0d86a5ab5..e93c6ba89 100644
+--- a/src/test/test_util.c
++++ b/src/test/test_util.c
+@@ -5829,13 +5829,9 @@ test_util_monotonic_time(void *arg)
+   /* We need to be a little careful here since we don't know the system load.
+    */
+   tt_i64_op(monotime_diff_msec(&mt1, &mt2), OP_GE, 175);
+-  tt_i64_op(monotime_diff_msec(&mt1, &mt2), OP_LT, 1000);
+   tt_i64_op(monotime_coarse_diff_msec(&mtc1, &mtc2), OP_GE, 125);
+-  tt_i64_op(monotime_coarse_diff_msec(&mtc1, &mtc2), OP_LT, 1000);
+   tt_u64_op(nsec2-nsec1, OP_GE, 175000000);
+-  tt_u64_op(nsec2-nsec1, OP_LT, 1000000000);
+   tt_u64_op(nsecc2-nsecc1, OP_GE, 125000000);
+-  tt_u64_op(nsecc2-nsecc1, OP_LT, 1000000000);
+ 
+   tt_u64_op(msec1, OP_GE, nsec1 / 1000000);
+   tt_u64_op(usec1, OP_GE, nsec1 / 1000);
+@@ -5849,7 +5845,6 @@ test_util_monotonic_time(void *arg)
+   uint64_t coarse_stamp_diff =
+     monotime_coarse_stamp_units_to_approx_msec(stamp2-stamp1);
+   tt_u64_op(coarse_stamp_diff, OP_GE, 120);
+-  tt_u64_op(coarse_stamp_diff, OP_LE, 1200);
+ 
+   {
+     uint64_t units = monotime_msec_to_approx_coarse_stamp_units(5000);