[grilo-plugins] meson: do not use absolute path

[Victor Toso de Carvalho <victortoso src gnome org>]

commit 0238bc5e203c5f77638ea3ea24441e3de6b1cad3
Author: Victor Toso <me victortoso com>
Date:   Tue Feb 28 12:02:41 2017 +0100

    meson: do not use absolute path
    
    This patch fixes the build with meson v0.39+
    
    Running meson without this patch fails with:
    
    > Meson encountered an error in file src/dleyna/meson.build, line 38,
    > column 0: Tried to form an absolute path to a source dir. You should
    > not do that but use relative paths instead.
    >
    > To get include path to any directory relative to the current dir do
    
    > incdir = include_directories(dirname)

 meson.build            |    2 ++
 src/dleyna/meson.build |    4 +---
 2 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/meson.build b/meson.build
index 41a692a..354dda5 100644
--- a/meson.build
+++ b/meson.build
@@ -147,6 +147,8 @@ endforeach
 
 gnome = import('gnome')
 
+rootdir = include_directories('.')
+
 subdir('src')
 subdir('help')
 subdir('po')
diff --git a/src/dleyna/meson.build b/src/dleyna/meson.build
index cce17f4..eee2e64 100644
--- a/src/dleyna/meson.build
+++ b/src/dleyna/meson.build
@@ -40,9 +40,7 @@ shared_library('grldleyna',
     install: true,
     install_dir: pluginsdir,
     dependencies: must_deps + plugins[dleyna_idx][REQ_DEPS] + plugins[dleyna_idx][OPT_DEPS],
-    include_directories: include_directories([
-        meson.build_root(),
-    ]),
+    include_directories: rootdir,
     c_args: [
         '-DG_LOG_DOMAIN="GrlDleyna"',
         '-DHAVE_CONFIG_H',