Add back kqueue support on iOS (#716)

Author: xiazhvera

CMakeLists.txt

@@ -110,10 +110,8 @@ elseif (APPLE)
         list(APPEND EVENT_LOOP_DEFINES "DISPATCH_QUEUE")
     endif ()
 
-    # Enable KQUEUE on MacOS 
-    if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
-        list(APPEND EVENT_LOOP_DEFINES "KQUEUE")
-    endif()
+   # Enable KQUEUE on APPLE platforms
+    list(APPEND EVENT_LOOP_DEFINES "KQUEUE")
 
 elseif (CMAKE_SYSTEM_NAME STREQUAL "FreeBSD" OR CMAKE_SYSTEM_NAME STREQUAL "NetBSD" OR CMAKE_SYSTEM_NAME STREQUAL "OpenBSD")
     file(GLOB AWS_IO_OS_HEADERS