[pygobject] Don't import inspect at module level

[Christoph Reiter <creiter src gnome org>]

commit 98726caff183491cde1e145861adfcff0c243d9b
Author: Christoph Reiter <creiter src gnome org>
Date:   Sun Oct 4 09:53:27 2015 +0200

    Don't import inspect at module level
    
    Move it to the only user instead as importing inspect
    takes 10msec here.

 gi/_signalhelper.py |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gi/_signalhelper.py b/gi/_signalhelper.py
index 47e6e2f..30ff541 100644
--- a/gi/_signalhelper.py
+++ b/gi/_signalhelper.py
@@ -18,7 +18,6 @@
 # License along with this library; if not, see <http://www.gnu.org/licenses/>.
 
 import sys
-import inspect
 
 from ._gi import _gobject
 
@@ -220,6 +219,8 @@ def get_signal_annotations(func):
     return_type = None
 
     if hasattr(func, '__annotations__'):
+        # import inspect only when needed because it takes ~10 msec to load
+        import inspect
         spec = inspect.getfullargspec(func)
         arg_types = tuple(spec.annotations[arg] for arg in spec.args
                           if arg in spec.annotations)