[TSan] Turn on ignore_interceptors_accesses

This was already done on [swift-5.1-branch], but I forgot to also
apply the change to [upstream-with-swift]:

This flag is usually enabled on Darwin. Turn it on unconditionally for
Swift, even on Linux.

Reason: Silences the remaining false positives for TSan in the swift-nio
test suite.

rdar://52215193

apple-llvm-split-commit: 0f52cc47d62a27311bf4b92d9d25584d7936be11
apple-llvm-split-dir: compiler-rt/

Author: yln

compiler-rt/lib/tsan/rtl/tsan_flags.inc

@@ -76,7 +76,7 @@ TSAN_FLAG(int, io_sync, 1,
 TSAN_FLAG(bool, die_after_fork, true,
           "Die after multi-threaded fork if the child creates new threads.")
 TSAN_FLAG(const char *, suppressions, "", "Suppressions file name.")
-TSAN_FLAG(bool, ignore_interceptors_accesses, false,
+TSAN_FLAG(bool, ignore_interceptors_accesses, true,
           "Ignore reads and writes from all interceptors.")
 TSAN_FLAG(bool, ignore_noninstrumented_modules, true,
           "Interceptors should only detect races when called from instrumented "