Move EMotionFX's OpenGL dependency to 3rd Party and make sure Mac builds successfully

cmake/3rdParty/Platform/Mac/OpenGLInterface_mac.cmake

@@ -0,0 +1,16 @@
+#
+# All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
+# its licensors.
+#
+# For complete copyright and license terms please see the LICENSE at the root of this
+# distribution (the "License"). All use of this software is governed by the License,
+# or, if provided, by the license below or the license accompanying this file. Do not
+# remove or modify any license notices. This file is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#
+
+target_compile_definitions(3rdParty::OpenGLInterface
+    INTERFACE
+        # MacOS 10.14 deprecates OpenGL. This silences the warnings for now.
+        GL_SILENCE_DEPRECATION
+)

cmake/3rdParty/Platform/Mac/cmake_mac_files.cmake

@@ -15,6 +15,7 @@ set(FILES
     Clang_mac.cmake
     DirectXShaderCompiler_mac.cmake
     FbxSdk_mac.cmake
+    OpenGLInterface_mac.cmake
     OpenSSL_mac.cmake
     Wwise_mac.cmake
 )