`LDFLAGS` and `LIBS` not used consistently in `configure`

[zanieb]

Bug report

Bug description:

Following up on #128322, I noticed that the same pattern of setting LDFLAGS instead of LIBS is used frequently. Additionally, there is not consistency in the ordering of the added libraries, e.g., LIBS="$LIBS ..." vs LIBS="... $LIBS".

For cases where the linking order matters, I believe using LDFLAGS is incorrect and the existing $LIBS should always come first.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-128354: Use LIBS consistently over LDFLAGS in library build checks #128359
• [3.13] gh-128354: Consistently use LIBS over LDFLAGS in library build… #128465
• [3.12] gh-128354: Consistently use LIBS over LDFLAGS in library build… #128466

[hugovk]

@zanieb Thanks for the PR, now merged and backported! Can we close this issue now?