[PATCH] [libcxxabi] Teach CMake better ways to find the libc++ source directory (and misc cleanup).

[Dan Albert]

LGTM with at least the doc fix and the change to `sys.path.insert` (either change I mentioned is fine).


================
Comment at: test/lit.cfg:33
@@ +32,3 @@
+libcxx_test_src_root = os.path.join(libcxx_src_root, 'test')
+if os.path.isdir(libcxx_test_src_root):
+    sys.path.insert(0, libcxx_test_src_root)
----------------
`os.path.isfile(os.path.join(libcxx_test_src_root, 'libcxx', '__init__.py'))` is slightly more correct.

================
Comment at: test/lit.cfg:34
@@ -35,1 +33,3 @@
+if os.path.isdir(libcxx_test_src_root):
+    sys.path.insert(0, libcxx_test_src_root)
 else:
----------------
Apparently should use 1 rather than 0: http://stackoverflow.com/a/10097543/632035

Though in this case there's really no reason you can't just append it (or use `site.addsitedir`).

================
Comment at: www/index.html:93
@@ -92,2 +92,3 @@
   <ul>
+  <li>Check out the libcxx source tree.</li>
   <li><code>cd libcxxabi</code></li>
----------------
Make a link to the instructions on the libcxx page.

http://reviews.llvm.org/D7130

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/