civetweb: add .gitignore

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/src/civetweb b/src/civetweb
index 8a07012185851b8e8be180391866b5995c10ee93..af76623303242ba3157fef19134f27efd38977e0 160000 (submodule)
--- a/src/civetweb
+++ b/src/civetweb
@@ -1 +1 @@
-Subproject commit 8a07012185851b8e8be180391866b5995c10ee93
+Subproject commit af76623303242ba3157fef19134f27efd38977e0