Eliminate the -chained-pch flag and all of the frontend and libclang options associated with it. Chained PCH is the only way to build a PCH file that includes another PCH file

llvm-svn: 138597
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index e16a21e..7c32250 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -824,18 +824,18 @@
    */
   CXTranslationUnit_CacheCompletionResults = 0x08,
   /**
-   * \brief Enable precompiled preambles in C++.
+   * \brief DEPRECATED: Enable precompiled preambles in C++.
    *
    * Note: this is a *temporary* option that is available only while
-   * we are testing C++ precompiled preamble support.
+   * we are testing C++ precompiled preamble support. It is deprecated.
    */
   CXTranslationUnit_CXXPrecompiledPreamble = 0x10,
 
   /**
-   * \brief Enabled chained precompiled preambles in C++.
+   * \brief DEPRECATED: Enabled chained precompiled preambles in C++.
    *
    * Note: this is a *temporary* option that is available only while
-   * we are testing C++ precompiled preamble support.
+   * we are testing C++ precompiled preamble support. It is deprecated.
    */
   CXTranslationUnit_CXXChainedPCH = 0x20,