Fix getting absolute path to YAML_PATH

When we extend the `YAML_PATH` in bb or bbappend,
the meson.project_source_root should not get the absolute path in
meson.build, this will produce double paths and cause the build to
fail.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I6de51da8b9fda4d00a727211edd3448802f84a43
2 files changed