Fix a crasher due to an assert when two files have the same UUID but different paths.

Summary: The PlaceholderObjectFile has an assert in SetLoadAddress that fires if "m_base == value" is not true. To avoid this, we create check that the base address matches, and if it doesn't we clear the module that was found using the UUID so that we create a new PlaceholderObjectFile. Added a test to cover this issue.

Reviewers: labath, aadsm, dvlahovski

Subscribers: lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D68106

llvm-svn: 374242