ENH: force c++ when building c++ objects

Modules/Platform/AIX.cmake

@@ -38,6 +38,8 @@ IF(NOT CMAKE_COMPILER_IS_GNUCC)
 ENDIF(NOT CMAKE_COMPILER_IS_GNUCC)
 
 IF(NOT CMAKE_COMPILER_IS_GNUCXX)
+  SET(CMAKE_CXX_COMPILE_OBJECT
+    "<CMAKE_CXX_COMPILER> -+ <FLAGS> -o <OBJECT> -c <SOURCE>")
   SET (CMAKE_CXX_CREATE_PREPROCESSED_SOURCE "<CMAKE_CXX_COMPILER> <FLAGS> -E <SOURCE> > <PREPROCESSED_SOURCE>")
   SET (CMAKE_CXX_CREATE_ASSEMBLY_SOURCE "<CMAKE_CXX_COMPILER> <FLAGS> -S <SOURCE> -o <ASSEMBLY_SOURCE>")
 ENDIF(NOT CMAKE_COMPILER_IS_GNUCXX)