jit: Adjust back-patch of f90b4a84 to 12 and 13.

jit: Adjust back-patch of f90b4a84 to 12 and 13.

While back-patching f90b4a84, I missed that branches before
REL_14_STABLE did some (accidental?) type punning in a function
parameter, and failed to adjust these two branches accordingly.  That
didn't seem to cause a problem for newer LLVM versions or non-debug
builds, but older debug builds would fail a type cross-check assertion.
Fix by supplying the correct function argument type.  In REL_14_STABLE
the same change was made by commit df99ddc7.

Per build farm animal xenodermus, which runs a debug build of LLVM 6
with jit_above_cost=0.

Discussion: https://postgr.es/m/CA%2BhUKGLQ38rgZ3bvNHXPRjsWFAg3pa%3Dtnpeq0osa%2B%3DmiFD5jAw%40mail.gmail.com