Remove fontconfig TSan suppression

Per https://crbug.com/795110#c3, newer fontconfigs are threadsafe.
https://bugs.chromium.org/p/skia/issues/detail?id=1497 suggests the relevant
version is 2.10.91. third_party/fontconfig is newer than that now, so remove
the suppression.

Bug: 795110
Change-Id: Ib9297814d682e75278c6d9d78d6c7d5315b5fce1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1643027
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Auto-Submit: David Benjamin <davidben@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665931}

build/sanitizers/tsan_suppressions.cc

@@ -169,9 +169,6 @@ char kTSanDefaultSuppressions[] =
     "race:base::debug::SetCrashKeyString\n"
     "race:crash_reporter::internal::CrashKeyStringImpl::Set\n"
 
-    // http://crbug.com/795110
-    "race:third_party/fontconfig/*\n"
-
     // http://crbug.com/927330
     "race:net::(anonymous namespace)::g_network_change_notifier\n"