shorten SharedMutex tests that timeout under ASAN

Summary:New ASAN options are more thorough but slower, resulting
in timeouts for some tests.  Decreasing their internal loop count to
compensate.

Reviewed By: yfeldblum

Differential Revision: D2973982

fb-gh-sync-id: 67391936d0b4930f99d00358ebb93a1b3ee87140
shipit-source-id: 67391936d0b4930f99d00358ebb93a1b3ee87140

folly/test/SharedMutexTest.cpp

@@ -1001,14 +1001,14 @@ TEST(SharedMutex, deterministic_mixed_mostly_read_write_prio) {
 TEST(SharedMutex, mixed_mostly_read_read_prio) {
   for (int pass = 0; pass < 5; ++pass) {
     runMixed<atomic, SharedMutexReadPriority, TokenLocker>(
-        50000, 32, 0.1, false);
+        10000, 32, 0.1, false);
   }
 }
 
 TEST(SharedMutex, mixed_mostly_read_write_prio) {
   for (int pass = 0; pass < 5; ++pass) {
     runMixed<atomic, SharedMutexWritePriority, TokenLocker>(
-        50000, 32, 0.1, false);
+        10000, 32, 0.1, false);
   }
 }