weechat: add pkg-config as a build-time dependency
weechat: add pkg-config as a build-time dependency

Manually running configure leads to

  checking for pkg-config... no
  configure: error:
  *** "pkg-config" couldn't be found on your system.
  *** Try to install it with your software package manager.

Correspondingly, cmake doesn't end up checking for lua, etc.

Adding pkg-config as a build-time dependency allows the options
specified in the formula to be found.

This was noticed by a user using the option --with-lua, which didn't
result in the lua plugin getting built.

Closes #49262

Closes #49294.

Signed-off-by: Dominyk Tiller <53e438f55903875d07efdd98a8aaf887e7208dd3@gmail.com>

filcab/homebrew,filcab/homebrew,filcab/homebrew,filcab/homebrew