Remove workaround for borked sem_init library function.

src/base/platform/semaphore.cc

Index: src/base/platform/semaphore.cc
diff --git a/src/base/platform/semaphore.cc b/src/base/platform/semaphore.cc
index a7e522ae75f23d1541db3b78a022addac8ae3ec3..7c86f43b323f1b69febd4dbdb75deeb72525feb4 100644
--- a/src/base/platform/semaphore.cc
+++ b/src/base/platform/semaphore.cc
@@ -87,10 +87,6 @@ Semaphore::Semaphore(int count) {
       0, reinterpret_cast<uintptr_t>(&native_handle_) &
       kSemaphoreAlignmentMask);
   DCHECK(count >= 0);
-#if V8_LIBC_GLIBC
-  // sem_init in glibc prior to 2.1 does not zero out semaphores.
-  memset(&native_handle_, 0, sizeof(native_handle_));
-#endif
   int result = sem_init(&native_handle_, 0, count);
   DCHECK_EQ(0, result);
   USE(result);