[LanguageRuntime] Move ObjCLanguageRuntime into a plugin

Summary:
Following up to my CPPLanguageRuntime change, I'm moving
ObjCLanguageRuntime into a plugin as well.

Reviewers: JDevlieghere, compnerd, jingham, clayborg

Subscribers: mgorny, arphaman, lldb-commits

Differential Revision: https://reviews.llvm.org/D64763

llvm-svn: 366148
diff --git a/lldb/source/Symbol/ClangASTContext.cpp b/lldb/source/Symbol/ClangASTContext.cpp
index 2d40047..f85c5d2 100644
--- a/lldb/source/Symbol/ClangASTContext.cpp
+++ b/lldb/source/Symbol/ClangASTContext.cpp
@@ -86,7 +86,6 @@
 #include "lldb/Symbol/VerifyDecl.h"
 #include "lldb/Target/ExecutionContext.h"
 #include "lldb/Target/Language.h"
-#include "lldb/Target/ObjCLanguageRuntime.h"
 #include "lldb/Target/Process.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Utility/DataExtractor.h"
@@ -95,6 +94,7 @@
 #include "lldb/Utility/RegularExpression.h"
 #include "lldb/Utility/Scalar.h"
 
+#include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h"
 #include "Plugins/SymbolFile/DWARF/DWARFASTParserClang.h"
 #include "Plugins/SymbolFile/PDB/PDBASTParser.h"