[totem] build: Use idiomatic way of detecting Python3

[Bastien Nocera <hadess src gnome org>]

commit 18697d303d0cb9a0177167e0fc8b98722e19717c
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Aug 10 10:56:47 2017 +0200

    build: Use idiomatic way of detecting Python3
    
    And up the required Python version. We haven't supported running against
    Python2 since 2013, so try to detect a Python3 newer than "3.0".
    
    This also fixes running "python --version" (call had incorrect syntax)
    and gathering the version number (version appears on stdout, not stderr
    like it did for Python2).
    
    https://bugzilla.gnome.org/show_bug.cgi?id=786082

 meson.build |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/meson.build b/meson.build
index efb961f..c041657 100644
--- a/meson.build
+++ b/meson.build
@@ -211,12 +211,12 @@ python_deps = []
 
 python_option = get_option('enable-python')
 if python_option != 'no'
-  python = find_program('python', required: false)
+  python = import('python3').find_python()
   if python.found()
-    python_req_version = '>= 2.3'
+    python_req_version = '>= 3.0'
 
-    r = run_command(python, '--version')
-    python_version = r.stderr().split(' ')[1]
+    r = run_command([python, '--version'])
+    python_version = r.stdout().split(' ')[1]
 
     pygobject_dep = dependency('pygobject-3.0', version: '>= 2.90.3', required: false)
     pylint = find_program('pylint', required: false)