Add support for building Sphinx documentation when being built inside LLVM...

Add support for building Sphinx documentation when being built inside LLVM source tree and using CMake.

Patch by Dan Liew <daniel.liew@imperial.ac.uk>!

llvm-svn: 206662

lld/CMakeLists.txt

@@ -180,3 +180,5 @@ add_subdirectory(test)
 if (LLVM_INCLUDE_TESTS AND NOT LLD_BUILT_STANDALONE)
   add_subdirectory(unittests)
 endif()
+
+add_subdirectory(docs)

lld/docs/CMakeLists.txt

+if (LLVM_ENABLE_SPHINX)
+  if (SPHINX_FOUND)
+    include(AddSphinxTarget)
+    if (${SPHINX_OUTPUT_HTML})
+      add_sphinx_target(html lld)
+    endif()
+  endif()
+endif()