wayland: fix build break in yocto

In some thirdpart building system, eg. yocto. when generate protocol
code file, the file will be put out side of the source dir, As a result,
below build break will happen:

fatal error: xdg-shell-client-protocol.h: No such file or directory

need put the protocol code into source dir
24 jobs for fix_build_break in 40 minutes and 4 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Preparation
passed #365500
gst indent

00:00:51

passed #365499
manifest

00:00:39

 
  Build
passed #365506
build cerbero android universal

00:10:50

passed #365507
build cerbero cross win32

00:09:30

passed #365508
build cerbero cross win64

00:07:11

passed #365505
build cerbero fedora x86_64

00:07:12

manual #365510
gst-ios-12.2 allowed to fail manual
build cerbero ios universal
passed #365509
gst-macos-10.14
build cerbero macos x86_64

00:07:40

passed #365501
build fedora x86_64

00:10:26

passed #365502
build nodebug fedora x86_64

00:09:11

passed #365503
build static fedora x86_64

00:14:39

passed #365504
build static nodebug fedora x86_64

00:12:45

 
  Test
passed #365511
check fedora

00:03:59

passed #365512
integration testsuites fedora

00:08:34

passed #365516
valgrind bad

00:04:41

passed #365513
valgrind base

00:09:36

passed #365517
valgrind ges

00:05:44

passed #365653
valgrind good

00:09:30

passed #365515
valgrind ugly

00:03:25

failed #365603
valgrind good

00:11:13

failed #365588
valgrind good

00:12:09

failed #365514
valgrind good

00:16:42

 
  Integrate
passed #365518
android universal examples

00:05:26

passed #365519
documentation

00:03:17