Do no call sequence.unique on result of GLOB-RECURSIVELY.
That was an old hack which was only needed in one context -- when we
passed both Jamroot and jamroot as patterns, got back Jamroot and jamroot
(because windows is case-insensitive and reports that both exist), and get
confused.
Calling 'unique' does not harm in most cases, but in Boost Jamfiles we glob
for all headers, and O(n^2) algorithm used by unique considerably slows us.
[SVN r29187]
Vladimir Prus