Fixed relative locate_root path normalization

[Flast]

If the locate_root is specified as relative and trailing slashed, failed to open test log like this.

$ boost_regression/stage/bin/process_jam_log --boost-root /path/to/boost_root/ --locate-root results/ --input-file results/bjam.log
...
*****Warning - can't open output file: /path/to/results/./ost/bin.v2/libs/fusion/test/transform.test/gcc-8/debug/cxxstd-14-iso/visibility-hidden/test_log.xml