Change suggested by Ralf Corsepius:
I am not sure if this is related to this problem, but here is an observation:
All config.sub scripts from rtems' intrastructure packages internally
transform i386-rtems into i386-pc-rtems
newlib-1.8.0-rtems/config.sub i386-rtems --> i386-pc-rtems
egcs-1.0/config.sub i386-rtems ---> i386-pc-rtems
egcs-1.0.1/config.sub i386-rtems ---> i386-pc-rtems
bintutils-2.8.1.0.19/config.sub i386-rtems ---> i386-pc-rtems
gas-98xxxx/config.sub i386-rtems ---> i386-pc-rtems
The only exception is rtems itself:
rtems/config.sub i386-rtems ---> i386-rtems
I am not sure if this influences i386-rtems + c++/posix, but this indicates
that rtems' config.sub script should to be updated.
To fix this, simply copying config.sub e.g. from egcs and removing all
i[3456]-rtems* case statement lines from configure.in should be sufficient.
BTW, from autoconf's point of view i386-pc-rtems is the correct target
conforming autoconf's naming conventions, but using i386-rtems for all
packages (infrastructure and rtems) should make no difference.