Rename path() -> getPath().

Differential Revision: http://llvm-reviews.chandlerc.com/D1853

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@192167 91177308-0d34-0410-b5e6-96231b3b80d8
Rename GnuLd's path() too.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@192169 91177308-0d34-0410-b5e6-96231b3b80d8
Move duplicate code in InputGraphs to the parent class.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@192170 91177308-0d34-0410-b5e6-96231b3b80d8