G ++ header includes list by default

When compiling using cross g ++ on a Linux machine (lubuntu 11.10) in verbose mode, I can see a list of standard default header directories:

#include <...> search starts here:
/opt/eldk-4.2/usr/bin/../lib/gcc/powerpc-linux/4.2.2/include
/opt/eldk-4.2/ppc_4xx/usr/include/c++/4.2.2/opt/eldk-4.2/ppc_4xx/usr/include/c++/4.2.2/powerpc-linux
/opt/eldk-4.2/ppc_4xx/usr/include/c++/4.2.2/backward
/opt/eldk-4.2/usr/../ppc_4xx/usr/include

By executing the same g ++ file on another Linux machine (lubuntu 12.10), I get another list with fewer elements:

#include <...> search starts here:
/opt/eldk-4.2/usr/bin/../lib/gcc/powerpc-linux/4.2.2/include

and in which some of the Elms seem bad, as shown below:

ignoring nonexistent directory "/opt/ppc_4xx/usr/lib/gcc/powerpc-linux/includ../include/c++/4.2.2"

As a result, some compilations of the code in the first system do not compile on the second, because some headers were not found.

Why is this happening? Where does this list come from? Who is responsible for its creation ?. Is it easy to change it?

Any help is appreciated.