Comments: More comments on functions/globals in standard.h.
Summary: Backport of Core PR11058
Test Plan:
make check
Reviewers: #bitcoin_abc, Mengerian, markblundeberg
Reviewed By: #bitcoin_abc, Mengerian, markblundeberg
Subscribers: Fabien, markblundeberg, Mengerian
Differential Revision: https://reviews.bitcoinabc.org/D3113