Add .so to .gitignore.

Change-Id: I5418606cb51a43a8cd7f91f26448cf0e8dde1016
diff --git a/.gitignore b/.gitignore
index 2ccf83f..cb0347f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -39,6 +39,7 @@
 *.lo
 *.la
 src/.libs
+*.so
 
 .dirstamp