* defs.h (gdb_osabi): New enum value GDB_OSABI_AIX.

    * defs.h (gdb_osabi): New enum value GDB_OSABI_AIX.
        * osabi.c (gdb_osabi_name): Add name of new value GDB_OSABI_AIX.
        * rs6000-tdep.h: New file.
        * rs6000-tdep.c: Include "rs6000-tdep.h".
        (rs6000_gdbarch_init): Remove enabling of software single step.
        Will be done in the AIX-specific initialization routine.
        * rs6000-aix-tdep.c: New file.
        * config/powerpc/aix.mt (TDEPFILES): Add rs6000-aix-tdep.o.
        * Makefile.in (rs6000_tdep_h): New variable.
        (rs6000-tdep.o): Update dependencies.
        (rs6000-aix-tdep.o): New rule.