config: update deprecated autoconf macros

[hzhou]

Pull Request Description

To suppress warnings from autoconf 2.70 and later.

Fix/suppress warnings from pgcc/nvc.

Expected Impact

Author Checklist

• [x] Reference appropriate issues (with "Fixes" or "See" as appropriate)
• [x] Commits are self-contained and do not do two things at once
• [x] Commit message is of the form: module: short description and follows good practice
• [x] Add comments such that someone without knowledge of the code could understand
• [x] Have read and agree to the Yaksa CLA terms (https://github.com/pmodels/yaksa/wiki/Yaksa-Contributor-License-Agreement)