asio: update to 1.18.1.

[unspecd]

General

• This is a new package and it conforms to the quality requirements

Have the results of the proposed changes been tested?

• I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me
• I generally don't use the affected packages but briefly tested this PR

Does it build and run successfully?

• I built this PR locally for my native architecture, x86_64-musl
• I built this PR locally for these architectures:
  • aarch64-musl
  • armv7l
  • armv6l-musl

[unspecd]

pre_configure is no longer needed since 713a9ae.