Merge branch 'bw/realpath-wo-chdir'

The implementation of "real_path()" was to go there with chdir(2) and call getcwd(3), but this obviously wouldn't be usable in a threaded environment. Rewrite it to manually resolve relative paths including symbolic links in path components. * bw/realpath-wo-chdir: real_path: set errno when max number of symlinks is exceeded real_path: prevent redefinition of MAXSYMLINKS