Revert "make aix build ignore yacc warning"

This reverts commit a1fe8a5b529d137ec46cd4e4ec4c01db8705fe98.

Build on Solaris 10 started failing after this commit.
tells yacc that we expect some reduce/shift conflicts to happen

(cherry picked from commit 3c9d282e3afdac5216f7aeb70cb69bb864106390)