config error if you pass --enable-wayland-only or --enable-wayland-clients without...

config error if you pass --enable-wayland-only or --enable-wayland-clients without wayland required packages to avoid later build fail

Summary:
You can get build error if you don't have required packages for wayland configuration such as pixman-1.
I think it would be good to know you about package error at configuration time.

Test Plan:
1. change your name of pixman-1.pc file temporarily.
2. also change your name of pixman.h file temporarily.
3. config e with --enable-wayland-clients option
4. make

Reviewers: raster, devilhorns, zmike

CC: cedric, stefan_schmidt
Differential Revision: https://phab.enlightenment.org/D782