Fix a bug where an unspecified logdir in a child process would use <install>/logs as the logdir, eventually aborting the child.
Fix a bug where an unspecified logdir in a child process would use <install>/logs as the logdir, eventually aborting the child.

git-svn-id: fe3cd4388a6e5a968b09397a3d721fe124e8117a@554 5b54908e-ead4-fc18-b48a-0285e6dbc711

rnk/drmemory,rnk/drmemory,rnk/drmemory,rnk/drmemory