Two patches to fix the broken build.

One to fix a C++ compiler warning.
One to allow Sphinx to find a new document.

docs/TableGen/index.rst

@@ -9,6 +9,7 @@ TableGen Overview
    :hidden:
 
    BackEnds
+   BackGuide
    ProgRef
    Deficiencies
 
@@ -276,7 +277,9 @@ Pre-processed output should be used if the same information needs to be used
 in different contexts (like Instruction names), so your back-end should print
 a meta-information list that can be shaped into different compile-time formats.
 
-See the `TableGen BackEnds <BackEnds.html>`_ for more information.
+See :doc:`TableGen BackEnds <./BackEnds>` for a list of available
+backends, and see the :doc:`TableGen Backend Developer's Guide <./BackGuide>`
+for information on how to write a new backend.
 
 TableGen Deficiencies
 =====================

lib/TableGen/TableGenBackendSkeleton.cpp

@@ -47,6 +47,8 @@ public:
 
 void SkeletonEmitter::run(raw_ostream &OS) {
   emitSourceFileHeader("Skeleton data structures", OS);
+
+  (void)Records; // To suppress unused variable warning; remove on use.
 }
 
 namespace llvm {