libxvmc: reorganize configure flags, fix syntax
libxvmc: reorganize configure flags, fix syntax

Signed-off-by: Maxim Belkin <032baa6ccf1d4eaa4536fc4f9b83b9a1f593449a@gmail.com>

Linuxbrew/homebrew-xorg,maxim-belkin/homebrew-xorg,LinuxbrewTestBot/homebrew-xorg