doc: generate alias doc for large-count APIs (2nd try)

[hzhou]

Pull Request Description

Last commit ae7bba3 didn't create html pages for large count routines. That commit was a bit hackish by assuming the content pattern of the man page, and we can't reuse the same hack for html aliases since html docs are independent from man pages in principle.

This commit revise the mechanism by generating a poly_aliases list file during binding/mansrc generation, thus a more robust mechanism.

References #7112 Fixes #7116 [skip warnings]

Author Checklist

• [x] Provide Description Particularly focus on why, not what. Reference background, issues, test failures, xfail entries, etc.
• [x] Commits Follow Good Practice Commits are self-contained and do not do two things at once. Commit message is of the form: module: short description Commit message explains what's in the commit.
• [x] Passes All Tests Whitespace checker. Warnings test. Additional tests via comments.
• [x] Contribution Agreement For non-Argonne authors, check contribution agreement. If necessary, request an explicit comment from your companies PR approval manager.

[hzhou]

Locally verified:

[release ~/build/4.3.0a1] ls share/man/man3/*_c.3 |wc
    168     168    6239
[release ~/build/4.3.0a1] ls share/doc/mpich/www3/*_c.html |wc
    168     168    7751
[release ~/build/4.3.0a1] cat share/doc/mpich/www3/MPI_Allgather_c.html
<meta http-equiv="refresh" content="0; url=MPI_Allgather.html">
[release ~/build/4.3.0a1] cat share/man/man3/MPI_Allgather_c.3
.so man3/MPI_Allgather.3
[release ~/build/4.3.0a1]