[totem/wip/hadess/python-requires-gi] build; Python support requires introspection support

[Bastien Nocera <hadess src gnome org>]

commit 549b8e2bb884a40e8ceb9994ec09273e4fc8531b
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Feb 7 14:03:02 2019 +0100

    build; Python support requires introspection support
    
    So error out if Python support is requested but introspection isn't
    available, or disable Python support if not explicitely enabled.
    
    The Vala support portion of the build system  already has similar code.
    
    Closes: #238

 meson.build | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/meson.build b/meson.build
index d46de94c0..e9266cf2c 100644
--- a/meson.build
+++ b/meson.build
@@ -206,6 +206,15 @@ if python_option != 'no'
       error(str)
     endif
     message(str + ', disabling Python support')
+  else
+    if not have_gir
+      str = 'Introspection support is required to enable Python plugins'
+      if python_option == 'yes'
+        error(str)
+      endif
+      message(str + ', disabling Python support')
+      have_python = false
+    endif
   endif
 endif