libx11: fix for Linuxbrew
libx11: fix for Linuxbrew

* add a dependency on `util-macros`
* stylistic improvements

Signed-off-by: Maxim Belkin <032baa6ccf1d4eaa4536fc4f9b83b9a1f593449a@gmail.com>
Linuxbrew/homebrew-xorg,maxim-belkin/homebrew-xorg,LinuxbrewTestBot/homebrew-xorg