Don't try to ignore the SIGPIPE signal if it isn't defined

Summary: Which is the case when compiling under MSVC.

Reviewed By: pixelb

Differential Revision: D3671357

fbshipit-source-id: b7e51479cae44933c3f1caa21d45775a32f294a3

folly/io/async/test/AsyncSSLSocketTest.cpp

@@ -1890,6 +1890,7 @@ TEST(AsyncSSLSocketTest, ConnectTFOFallbackTimeout) {
 
 } // namespace
 
+#ifdef SIGPIPE
 ///////////////////////////////////////////////////////////////////////////
 // init_unit_test_suite
 ///////////////////////////////////////////////////////////////////////////
@@ -1901,3 +1902,4 @@ struct Initializer {
 };
 Initializer initializer;
 } // anonymous
+#endif

folly/io/async/test/AsyncSSLSocketTest2.cpp

@@ -131,7 +131,9 @@ TEST(AsyncSSLSocketTest2, AttachDetachSSLContext) {
 }  // folly
 
 int main(int argc, char *argv[]) {
+#ifdef SIGPIPE
   signal(SIGPIPE, SIG_IGN);
+#endif
   folly::SSLContext::setSSLLockTypes({
       {CRYPTO_LOCK_EVP_PKEY, folly::SSLContext::LOCK_NONE},
       {CRYPTO_LOCK_SSL_SESSION, folly::SSLContext::LOCK_SPINLOCK},