FindMagnum: provide MAGNUM_APPLICATION_{LIBRARIES,INCLUDE_DIRS} aliases.

Convenience aliases to variables related to one particular *Application
component, defined if and only if exactly one *Application component is
requested and found. Meant to be used to simplify porting when each
platform uses different *Application library.

modules/FindMagnum.cmake

@@ -41,6 +41,10 @@
 #  MAGNUM_*_FOUND   - Whether the component was found
 #  MAGNUM_*_LIBRARIES - Component library and dependent libraries
 #  MAGNUM_*_INCLUDE_DIRS - Include dirs of module dependencies
+# If exactly one *Application component is requested and found, its
+# libraries and include dirs are also available in convenience aliases
+# MAGNUM_APPLICATION_LIBRARIES and MAGNUM_APPLICATION_INCLUDE_DIRS to
+# simplify porting.
 #
 # Features of found Magnum library are exposed in these variables:
 #  MAGNUM_TARGET_GLES   - Defined if compiled for OpenGL ES
@@ -283,6 +287,19 @@ foreach(component ${Magnum_FIND_COMPONENTS})
 
         # Don't expose variables w/o dependencies to end users
         mark_as_advanced(FORCE MAGNUM_${_COMPONENT}_LIBRARY _MAGNUM_${_COMPONENT}_INCLUDE_DIR)
+
+        # If this is application library, make it available also in global
+        # MAGNUM_APPLICATION_LIBRARIES and MAGNUM_APPLICATION_INCLUDE_DIRS. If
+        # these variables are already set, unset them to avoid ambiguity.
+        if(${component} MATCHES .+Application)
+            if(NOT DEFINED MAGNUM_APPLICATION_LIBRARIES AND NOT DEFINED MAGNUM_APPLICATION_INCLUDE_DIRS)
+                set(MAGNUM_APPLICATION_LIBRARIES ${MAGNUM_${_COMPONENT}_LIBRARIES})
+                set(MAGNUM_APPLICATION_INCLUDE_DIRS ${MAGNUM_${_COMPONENT}_INCLUDE_DIRS})
+            else()
+                unset(MAGNUM_APPLICATION_LIBRARIES)
+                unset(MAGNUM_APPLICATION_INCLUDE_DIRS)
+            endif()
+        endif()
     else()
         set(Magnum_${component}_FOUND FALSE)
     endif()