FindIce: Support finding both release and debug libraries

Search for both release and debug library variants, and use
SelectLibraryConfigurations to choose the appropriate
library.  Also add both release and debug libraries to the
imported targets.

Modules/FindIce.cmake

@@ -360,12 +360,20 @@ function(_Ice_FIND)
   foreach(component ${Ice_FIND_COMPONENTS})
     string(TOUPPER "${component}" component_upcase)
     set(component_cache "Ice_${component_upcase}_LIBRARY")
+    set(component_cache_release "${component_cache}_RELEASE")
+    set(component_cache_debug "${component_cache}_DEBUG")
     set(component_found "${component_upcase}_FOUND")
-    find_library("${component_cache}" "${component}"
+    find_library("${component_cache_release}" "${component}"
       HINTS ${ice_roots}
       PATH_SUFFIXES ${ice_library_suffixes}
-      DOC "Ice ${component} library")
-    mark_as_advanced("${component_cache}")
+      DOC "Ice ${component} library (release)")
+    find_library("${component_cache_debug}" "${component}d"
+      HINTS ${ice_roots}
+      PATH_SUFFIXES ${ice_library_suffixes}
+      DOC "Ice ${component} library (debug)")
+    include(${CMAKE_CURRENT_LIST_DIR}/SelectLibraryConfigurations.cmake)
+    select_library_configurations(Ice_${component_upcase})
+    mark_as_advanced("${component_cache_release}" "${component_cache_debug}")
     if(${component_cache})
       set("${component_found}" ON)
       list(APPEND Ice_LIBRARY "${${component_cache}}")
@@ -438,6 +446,8 @@ if(Ice_FOUND)
   foreach(_Ice_component ${Ice_FIND_COMPONENTS})
     string(TOUPPER "${_Ice_component}" _Ice_component_upcase)
     set(_Ice_component_cache "Ice_${_Ice_component_upcase}_LIBRARY")
+    set(_Ice_component_cache_release "Ice_${_Ice_component_upcase}_LIBRARY_RELEASE")
+    set(_Ice_component_cache_debug "Ice_${_Ice_component_upcase}_LIBRARY_DEBUG")
     set(_Ice_component_lib "Ice_${_Ice_component_upcase}_LIBRARIES")
     set(_Ice_component_found "${_Ice_component_upcase}_FOUND")
     set(_Ice_imported_target "Ice::${_Ice_component}")
@@ -445,9 +455,29 @@ if(Ice_FOUND)
       set("${_Ice_component_lib}" "${${_Ice_component_cache}}")
       if(NOT TARGET ${_Ice_imported_target})
         add_library(${_Ice_imported_target} UNKNOWN IMPORTED)
-        set_target_properties(${_Ice_imported_target} PROPERTIES
-          IMPORTED_LOCATION "${${_Ice_component_cache}}"
-          INTERFACE_INCLUDE_DIRECTORIES "${Ice_INCLUDE_DIR}")
+        if()
+          set_target_properties(${_Ice_imported_target} PROPERTIES
+            INTERFACE_INCLUDE_DIRECTORIES "${Ice_INCLUDE_DIR}")
+        endif()
+        if(EXISTS "${${_Ice_component_cache}}")
+          set_target_properties(${_Ice_imported_target} PROPERTIES
+            IMPORTED_LINK_INTERFACE_LANGUAGES "CXX"
+            IMPORTED_LOCATION "${${_Ice_component_cache}}")
+        endif()
+        if(EXISTS "${${_Ice_component_cache_debug}}")
+          set_property(TARGET ${_Ice_imported_target} APPEND PROPERTY
+            IMPORTED_CONFIGURATIONS DEBUG)
+          set_target_properties(${_Ice_imported_target} PROPERTIES
+            IMPORTED_LINK_INTERFACE_LANGUAGES_DEBUG "CXX"
+            IMPORTED_LOCATION_DEBUG "${${_Ice_component_cache_debug}}")
+        endif()
+        if(EXISTS "${${_Ice_component_cache_release}}")
+          set_property(TARGET ${_Ice_imported_target} APPEND PROPERTY
+            IMPORTED_CONFIGURATIONS RELEASE)
+          set_target_properties(${_Ice_imported_target} PROPERTIES
+            IMPORTED_LINK_INTERFACE_LANGUAGES_RELEASE "CXX"
+            IMPORTED_LOCATION_RELEASE "${${_Ice_component_cache_release}}")
+        endif()
       endif()
     endif()
     unset(_Ice_component_upcase)