Revision 672900

(THRIFT-40) Add -version switch to the compiler to show the Thrift version

The version is determined by configure.ac. After this version is shown the
revision. For subversion, it is simply the current revision as given by
`svnversion`. For git, the latest svn revision that HEAD includes is shown,
followed by the offset of HEAD from that commit, followed by a truncated sha1
for HEAD. If the offset is 0, the offset and sha1 are omitted.