Use llvm for dumping DWARF expressions

Summary:
It uses the new ability of ABI plugins to vend llvm::MCRegisterInfo
structs (which is what is needed to turn dwarf register numbers into
strings).

Reviewers: JDevlieghere, aprantl, jasonmolenda

Subscribers: tatyana-krasnukha, lldb-commits

Differential Revision: https://reviews.llvm.org/D67966

llvm-svn: 373208
diff --git a/lldb/source/Symbol/ClangASTContext.cpp b/lldb/source/Symbol/ClangASTContext.cpp
index eb86d11..78bad39 100644
--- a/lldb/source/Symbol/ClangASTContext.cpp
+++ b/lldb/source/Symbol/ClangASTContext.cpp
@@ -103,8 +103,8 @@
 
 using namespace lldb;
 using namespace lldb_private;
-using namespace llvm;
 using namespace clang;
+using llvm::StringSwitch;
 
 namespace {
 #ifdef LLDB_CONFIGURATION_DEBUG