Fix a crash in compile_to_object function

[libor.bukata@oracle.com]

On non-Linux platforms, gdb crashes when compile command is issued
because of the null pointer in struct osabi_names gdb_osab. The attached
patch adds a check to avoid this crash and adds osabi name for Solaris.
However, there is probably more work required to enable compile feature
on Solaris (e.g., solaris_infcall_munmap) and other platforms.

Thanks,
Libor
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