[libpeas] build: check for python3-embed for python 3.8

[Christian Hergert <chergert src gnome org>]

commit 454e72cd37ae562bd33cb6d1a7ddc93797cedd28
Author: Christian Hergert <chergert redhat com>
Date:   Mon Aug 5 17:11:49 2019 -0700

    build: check for python3-embed for python 3.8
    
    We have a new pkgconfig to check for when using python 3.8 so that we
    actually link against Python.
    
    See also:
    
      https://github.com/mesonbuild/meson/issues/5629
      https://github.com/libratbag/libratbag/commit/7de944aaa02a776a77d2f73b8e3b5962d9ecbfce

 meson.build | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 1869864..f73d986 100644
--- a/meson.build
+++ b/meson.build
@@ -104,8 +104,13 @@ gtk_dep = dependency('gtk+-3.0', version: gtk_req, required: false)
 gtk_doc_dep = dependency('gtk-doc', version: gtk_doc_req, required: false)
 gladeui_dep = dependency('gladeui-2.0', required: false)
 
+# From python 3.8 we neeed python3-embed
+python3_dep = dependency('python3-embed', required: false)
+if not python3_dep.found()
+  python3_dep = dependency('python3', version: python3_req, required: false)
+endif
+
 python2_dep = dependency('python2', version: python2_req, required: false)
-python3_dep = dependency('python3', version: python3_req, required: false)
 pygobject_dep = dependency('pygobject-3.0', version: pygobject_req, required: false)
 lua51_dep = dependency('lua5.1', version: lua_req, required: false)
 lua51_lgi_dep = dependency('lua5.1-lgi', version: lua_lgi_req, required: false)