Thrift: Compile without libevent.

Summary:
- Totally re-did the libevent check.
- Thrift now compiles and instals cleanly without libevent.
- (libevent is still needed to build libthriftnb.)

Reviewed By: mcslee

Test Plan:
- Ran configure and make in various configurations in my VMware.
- Clean build and install of Thrift on devrs004 (into /tmp).

Revert Plan: ok


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665267 13f79535-47bb-0310-9956-ffa450edef68
4 files changed