We don't add build-time dependency on Wayland libraries; that allows Wayland enabled Firefox
builds to run on systems without Wayland support.
We also can't dlsym() Wayland symbols directly from libwayland-client.so library as we miss
global data entries referenced by code at wayland-client.h then.
As a partial solution (for glibc systems only) we create dummy libwayland-client.so library
implementation and place it *after* Gtk+ 3.0 libraries at linking time.
It fixes build-time dependencies (we link against our libwayland-client.so library).
Run-time dependency is resolved by ld.so - when Gtk+ 3.0 libraries are linked with
system libwayland-client.so library, wayland symbols are pulled from there instead
from our dummy libwayland-client.so library.
When Gtk+ 3.0 is not linked with system libwayland-client.so it means we're running
on system without Wayland support. Our dummy libwayland-client.so implementation
is used (symbols are pulled run-time from there) and Firefox Wayland support is
disabled then.
MozReview-Commit-ID: IyaePwp4MxV
--HG--
extra : rebase_source : 852955d001657176e0bf69c099580be862d0b448
Martin Stransky