* config.gcc (rs6000-ibm-aix4.x): Delete.
        (rs6000-ibm-aix5.1): Delete.
        (rs6000-ibm-aix5.2): Delete.
        (rs6000-ibm-aix5.3): Delete.
        * config/rs6000/aix43.h: Delete.
        * config/rs6000/aix51.h: Delete.
        * config/rs6000/aix52.h: Delete.
        * config/rs6000/t-aix43: Delete.

From-SVN: r263506