fix COPY_UNITY for LINK_ONLY libraries

CMake/cotire.cmake

@@ -3133,13 +3133,24 @@ endfunction(cotire_target)
 function (cotire_map_libraries _strategy _mappedLibrariesVar)
 	set (_mappedLibraries "")
 	foreach (_library ${ARGN})
+		if (_library MATCHES "^\\$<LINK_ONLY:(.+)>$")
+			set (_libraryName "${CMAKE_MATCH_1}")
+			set (_linkOnly TRUE)
+		else()
+			set (_libraryName "${_library}")
+			set (_linkOnly FALSE)
+		endif()
 		if ("${_strategy}" MATCHES "COPY_UNITY")
-			cotire_is_target_supported(${_library} _isSupported)
+			cotire_is_target_supported(${_libraryName} _isSupported)
 			if (_isSupported)
 				# use target's corresponding unity target, if available
-				get_target_property(_libraryUnityTargetName ${_library} COTIRE_UNITY_TARGET_NAME)
+				get_target_property(_libraryUnityTargetName ${_libraryName} COTIRE_UNITY_TARGET_NAME)
 				if (TARGET "${_libraryUnityTargetName}")
-					list (APPEND _mappedLibraries "${_libraryUnityTargetName}")
+					if (_linkOnly)
+						list (APPEND _mappedLibraries "$<LINK_ONLY:${_libraryUnityTargetName}>")
+					else()
+						list (APPEND _mappedLibraries "${_libraryUnityTargetName}")
+					endif()
 				else()
 					list (APPEND _mappedLibraries "${_library}")
 				endif()