build-many-glibcs.py: Add openrisc hard float glibc variant

This adds the OpenRISC hard float glibc variant to the build many
script.  We update the compiler for glibc to support hard-float
multilibs to allow us to use a single generic compiler for all glibc
variants, this requires updating the compiler name.

Tested and all builds are passing.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>