EmulatorPkg/Unix/Host: Fix XCODE5 IA32/X64 build failure

https://bugzilla.tianocore.org/show_bug.cgi?id=2046

* Clean up XCODE5 IA32 [BuildOptions] and fix IA32
  X11 include path.
* Add -DEFIAPI=__attribute__((ms_abi)) to X64 XCODE5
  [BuildOptions]
* Use -target x86_64-apple-darwin for X64 XCODE5
  [BuildOptions]
* Add Wl,-no_pie to X64 XCODE5 [BuildOptions]
* Address function type mismatch reported by XCODE5
  in reverse gasket callback between UEFI ABI and
  MacOS ABI.  Use a UINTN to pass function address
  to assembly code.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Andrew Fish <afish@apple.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>

EmulatorPkg/Unix/Host/Pthreads.c

@@ -2,7 +2,7 @@
  POSIX Pthreads to emulate APs and implement threads
 
 Copyright (c) 2011, Apple Inc. All rights reserved.
-Copyright (c) 2011, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2011 - 2019, Intel Corporation. All rights reserved.<BR>
 
 SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -109,7 +109,7 @@ SecFakePthreadStart (
   // This is a great example of how all problems in computer
   // science can be solved by adding another level of indirection
   //
- return  (VOID *)ReverseGasketUint64 ((CALL_BACK)Start, (UINTN)Context);
+ return  (VOID *)ReverseGasketUint64 ((UINTN)Start, (UINTN)Context);
 }
 
 UINTN