canonicalize-lgpl: work around AIX realpath bug AIX 7.1 realpath() gets horribly confused by consecutive / in the name to be resolved. * m4/canonicalize.m4 (gl_FUNC_REALPATH_WORKS): Expose AIX bug. * doc/posix-functions/realpath.texi (realpath): Document it. Reported by Bruno Haible. Signed-off-by: Eric Blake <eblake@redhat.com>