disable VDSO getcpu optimization in MSAN build mode

Reviewed By: yfeldblum

Differential Revision: D19359860

fbshipit-source-id: b084d8cd603238e76d61de1eed3f233cf5b7fb27

folly/concurrency/CacheLocality.cpp

@@ -296,7 +296,7 @@ CacheLocality CacheLocality::uniform(size_t numCpus) {
 ////////////// Getcpu
 
 Getcpu::Func Getcpu::resolveVdsoFunc() {
-#if !FOLLY_HAVE_LINUX_VDSO
+#if !defined(FOLLY_HAVE_LINUX_VDSO) || defined(FOLLY_SANITIZE_MEMORY)
   return nullptr;
 #else
   void* h = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);

folly/concurrency/test/CacheLocalityTest.cpp

@@ -1033,7 +1033,7 @@ TEST(CacheLocality, BenchmarkSysfs) {
 }
 #endif
 
-#if FOLLY_HAVE_LINUX_VDSO
+#if defined(FOLLY_HAVE_LINUX_VDSO) && !defined(FOLLY_SANITIZE_MEMORY)
 TEST(Getcpu, VdsoGetcpu) {
   unsigned cpu;
   Getcpu::resolveVdsoFunc()(&cpu, nullptr, nullptr);