Merge bitcoin/bitcoin#22380: build: add and use C_STANDARD and CXX_STANDARD in depends

f7595f1354f4618436fdab232000dc152bff315a build: add and use CXX_STANDARD in depends (fanquake)
7e7b3e42fa98b584ae60513a6774037bf677b8ce build: add and use C_STANDARD in depends (fanquake)

Pull request description:

  By explicitly setting a C standard version we avoid any potential for issues/differences in libraries that may come about due to C STD version, as well as avoid potentially being opted into newer code / features in libraries when compiler defaults change (i.e as of 11.0.0, Clang now defaults to gnu17 over gnu11).

  This should be a no-op for our release builds, because it's just explicitly setting the default that is [already being used](https://github.com/fanquake/core-review/blob/master/compiler-defaults.md). However this is relevant for anyone building depends with a newer compiler.

  I found [one broken `__STDC_VERSION__` check in the](https://github.com/miniupnp/miniupnp/pull/552) miniupnpc header.

  At the same time, add `CXX_STANDARD` for setting our C++ standard, and use that over setting `-std=c++17` for cxx packages.

  Guix builds:
  ```bash
  ```

ACKs for top commit:
  dongcarl:
    Code Review ACK f7595f1354f4618436fdab232000dc152bff315a
  laanwj:
    Code review ACK f7595f1354f4618436fdab232000dc152bff315a

Tree-SHA512: 9255190d91ba3de20762b1d6af35c59d64f3d77a52bbe9a3f1dfb6bcf16daef66054ebef96b58e7285cd01bf613e69a78bd5e8681c21293e254f23d1fa7b0f71

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