Use 32-bit instructions only since currently there is no demand for a
larger address space.  Provide one multilib with FPU and AltiVec support
and one without.

gcc/ChangeLog

	* config/rs6000/rtems.h (CPP_OS_RTEMS_SPEC): Define __PPC_CPU_E6500__
	for -mcpu=e6500.
	* config/rs6000/t-rtems: Add e6500 multilibs.

From-SVN: r219387