Don't build the async signal handler test on Windows

Summary: `AsyncSignalHandler` is not currently supported on Windows, so we shouldn't be attempting to build it.

Reviewed By: yfeldblum

Differential Revision: D5437276

fbshipit-source-id: b3f281bfc501444bb22056860ee785a2beb9b671

CMakeLists.txt

@@ -410,7 +410,6 @@ if (BUILD_TESTS)
           AsyncSSLSocketTest.h
         SOURCES
           AsyncPipeTest.cpp
-          AsyncSignalHandlerTest.cpp
           AsyncSocketExceptionTest.cpp
           AsyncSocketTest.cpp
           AsyncSocketTest2.cpp
@@ -421,6 +420,8 @@ if (BUILD_TESTS)
           # This is disabled because it depends on things that don't exist
           # on Windows.
           #EventHandlerTest.cpp
+          # The async signal handler is not supported on Windows.
+          #AsyncSignalHandlerTest.cpp
       TEST async_timeout_test SOURCES AsyncTimeoutTest.cpp
       TEST AsyncUDPSocketTest SOURCES AsyncUDPSocketTest.cpp
       TEST DelayedDestructionTest SOURCES DelayedDestructionTest.cpp