How to add new path to BSP configure script

[rsg at alum.mit.edu (Robert S. Grimes)]

Hi,

I want to add an additional system include path to the configure script
for a new BSP.  It seems the place this should be is in the configure
script in the BSP root directory (e.g. libbsp/CPU/BSP/configure), but of
course this is created during the bootstrap process (right?).  In the
generated configure script, I found something like this:

    if test x"$rtems_cv_gcc_isystem" = xyes; then
      RTEMS_CPPFLAGS="-isystem \$(PROJECT_INCLUDE)"
    else
      RTEMS_CPPFLAGS="-I\$(PROJECT_INCLUDE)"
    fi

I want to change it to something like this:

    if test x"$rtems_cv_gcc_isystem" = xyes; then
      RTEMS_CPPFLAGS="-isystem \$(PROJECT_INCLUDE) -isystem \$(MY_INCLUDE)"
    else
      RTEMS_CPPFLAGS="-I\$(PROJECT_INCLUDE) -I\$(MY_INCLUDE)"
    fi

This assumes a configure call like this

    ../rtems-4.6.99.3/configure ... MY_INCLUDE=/some/relevant/path ...

So I have a few questions:

   1. Is this the right approach?
   2. If yes, then what needs to be modified to generated the new BSP
      configure script?
   3. If not, then what is the right approach?

Thanks!
-Bob