[Bug target/71375] Failure on startup on rs6000-ibm-aix{4.3|5.1.0}

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71375

--- Comment #2 from Segher Boessenkool <segher at gcc dot gnu.org> ---
aix52.h overrides TARGET_EXTRA_BUILTINS (sets it to 0); aix43.h and
aix51.h do not.  They probably should.