[PATCH] [libcxx] Update libc++ docs to include instructions for LIT.

[Marshall Clow]

Mostly good; a few comments.
I'd like to see more about using lit :-)

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Comment at: www/index.html:109
@@ +108,3 @@
+    clang (lack of C++11 language support disables some functionality). Note
+    that functinality provided by <atomic> is only functional with
+    clang.
----------------
Typo: 'functinality'.

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Comment at: www/index.html:213
@@ +212,3 @@
+  </p>
+
+  <!--=====================================================================-->
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I would add something here about using DYLD_LIBRARY_PATH to interpose the newly built dylib (say, for testing purposes).

Should probably remind people that (on a Mac) blindly copying these dylibs to /usr/lib will, if any error occurs, result in a system that will not boot.

http://reviews.llvm.org/D4766