ENH: Default to the same cmake used for configuring when building and installing. If none specified default to the cmake used to configure the outer/aggregating project.

Modules/AddExternalProject.cmake

@@ -398,7 +398,12 @@ function(add_external_project_build_command name)
     if(NOT cmd)
       set(cmd make)
       if(cfg_cmd_id STREQUAL "cmake")
-        set(cmd ${CMAKE_COMMAND})
+        get_target_property(cfg_cmd ${name} AEP_CONFIGURE_COMMAND)
+        if(cfg_cmd)
+          set(cmd ${cfg_cmd})
+        else()
+          set(cmd ${CMAKE_COMMAND})
+        endif()
       endif()
     endif()
 
@@ -443,7 +448,12 @@ function(add_external_project_install_command name)
     if(NOT cmd)
       set(cmd make)
       if(cfg_cmd_id STREQUAL "cmake")
-        set(cmd ${CMAKE_COMMAND})
+        get_target_property(cfg_cmd ${name} AEP_CONFIGURE_COMMAND)
+        if(cfg_cmd)
+          set(cmd ${cfg_cmd})
+        else()
+          set(cmd ${CMAKE_COMMAND})
+        endif()
       endif()
     endif()