Let GHCi work with with Sparc32+/V8+ .o files

Currently the GHCi linker looks exclusively for V7 ABI .o files.

You can generate V8+ ABI .o files using flags to gcc such as:
 -optc-mcpu=ultrasparc -opta-mcpu=ultrasparc

Note that this allows gcc to generate hardware integer division and
hardware floating point instructions rather than using software emulation.
All recent sparc hardware is V8+ or later. Perhaps we should check for the
cpu generation in configure and use the later ABI if possible.

Tested briefly on a SunBlade 100 (TI UltraSparc IIe) sparc-unknown-linux