[tracker] build: Require Meson >= 0.50

[Sam Thursfield <sthursfield src gnome org>]

commit 17777040c63b7bc8586fa77bfa1219c0d96a9dd9
Author: Sam Thursfield <sam afuera me uk>
Date:   Wed May 1 01:29:29 2019 +0200

    build: Require Meson >= 0.50
    
    Meson helpfully warns us that this is needed:
    
        WARNING: Project specifies a minimum meson_version '>=0.47' but uses features which were added in 
newer versions:
         * 0.50.0: {'install arg in configure_file'}

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index f5308ce00..8888bbc68 100644
--- a/meson.build
+++ b/meson.build
@@ -1,6 +1,6 @@
 project('tracker', 'c', 'vala',
         version: '2.2.1',
-        meson_version: '>=0.47')
+        meson_version: '>=0.50')
 
 gnome = import('gnome')
 i18n = import('i18n')