add PathGet.cc for getting paths. but it does not work without opt.
getAnalysis<callgraph> will be something error without real llvm pass.
so it needs be changed to a opt plugin.

Signed-off-by: xqx12 <xiaoqixue_1@163.com>
add xCallPaths.cc to get the call path in function and bb.
it could get end point from an xml file ,and calc the path from
entry to end by a dfs first search.
xintck: call this plugin named xCallPath.
Makefile.am: add flags needed by xmlparser and boost graph lib.

Signed-off-by: xqx12 <xiaoqixue_1@163.com>