Assorted minor cleanups for bootstrap-data Perl scripts.

Assorted minor cleanups for bootstrap-data Perl scripts.

FindDefinedSymbol was intended to take an array of possible include
paths, but it never actually worked correctly for any but the first
array element.  Since there's no use-case for more than one path
anyway, let's just simplify this code and its callers by redefining
it as taking only one include path.

Minor other code-beautification without functional effects, except
that in one place we format the output as pgindent would do.

John Naylor

Discussion: https://postgr.es/m/CAJVSVGXM_n32hTTkircW4_K1LQFsJNb6xjs0pAP4QC0ZpyJfPQ@mail.gmail.com