When using autoconf/automake to build Xwayland, the actual path to Xwayland is not fully qualified and refers to the "exec_prefix".
As a result, the path provided by the generated pkg-config file is wrong when using autoconf to build the Xserver.
Fix the xwayland.pc file to also set the variable "prefix" and "exec_prefix" so that the path to Xwayland is fully resolved in the resulting generated pkg-config file.
Add those variables to the meson build as well for good measure.
Signed-off-by: Olivier Fourdan email@example.com