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

[Eric Fiselier]

You can build libc++ in-tree? I did not know that!

1. I like that we are documenting the uniform CMake build system as the primary one. I'm not sure we should remove the buildit documentation right away though.
2. I agree that we should move towards using libc++abi as the primary ABI on linux as opposed to libsupc++ even though it must be explicitly linked.
3. I'm interested to hear what Mac users think about this patch. The documentation seems to reflect how I build and test libc++ on linux but that may not be the case on OS X.

I'll go through the actual instructions step-by-step tonight to do and in-tree build and out-of-tree build just to make sure nothing was omitted.

P.S. Sorry about hijacking this to deal with other documentation issues.

================
Comment at: www/index.html:107-110
@@ +106,6 @@
+  <p>
+    libc++ is known to work on the following platforms, using g++-4.2 and
+    clang (lack of C++11 language support disables some functionality). Note
+    that functinality provided by <atomic> is only functional with
+    clang.
+  </p>
----------------
I don't have access to a mac with g++-4.2 but is that still supported? libc++ requires a c++11 compiler to build so I'm skeptical GCC 4.2 works.
Along the same lines I don't think the comment about lack of C++11 is correct. I think we should update this to say that a C++11 compiler is required to build libc++.

================
Comment at: www/index.html:114-115
@@ +113,4 @@
+  <ul>
+    <li>Mac OS X i386</li>
+    <li>Mac OS X x86_64</li>
+  </ul>
----------------
When do you think we can say we officially support linux? 

================
Comment at: www/index.html:155-159
@@ -154,7 +166,11 @@
-  
+
+  <p>In-tree build:</p>
   <ul>
-    <li><code>cd libcxx/lib</code></li>
-    <li><code>export TRIPLE=-apple-</code></li>
-    <li><code>./buildit</code></li>
-    <li><code>ln -sf libc++.1.dylib libc++.dylib</code></li>
   </ul>
----------------
While I like documenting the CMake build system as the primary one since it is uniform across all systems should we be so quick to remove the documentation for the buildit script?

================
Comment at: www/index.html:199-204
@@ +198,8 @@
+  <ul>
+    <li><code>cd path/to/libcxx/libcxx</code></li>
+    <li><code>alias lit='python path/to/llvm/utils/lit/lit.py'</code></li>
+    <li><code>ln -s path/to/build/dir/projects/libcxx/test/lit.site.cfg
+        test/lit.site.cfg</code></li>
+    <li><code>lit -sv test/re/ # or whichever subset of tests you're interested
+        in</code></li>
+  </ul>
----------------
I'm very happy to see these instructions make it into the documentation. Since we are encouraging people to modify the source tree can we set up SVN to ignore libcxx/test/lit.site.cfg? (ex like a .gitignore file)

http://reviews.llvm.org/D4766