EmptyProject script is broken for macOS

[darksylinc]

System Information

• Ogre Version: 2.3 + master
• Operating System / Platform: macOS
• RenderSystem: Metal
• GPU: Any

Detailled description

EmptyProject should succeed.

Instead it fails because isOgreNext tries to do the following on line 80:

		set( DEBUG_SUFFIX "" )
		if( ${CMAKE_BUILD_TYPE} STREQUAL "Debug" )
			set( DEBUG_SUFFIX "_d" )
		endif()

But CMAKE_BUILD_TYPE is not set for XCode generator. See https://forums.ogre3d.org/viewtopic.php?p=555711#p555711

Additionally the paths it's trying to look into are probably wrong for macOS.