Instantiate llvm::Registry<clang::PluginASTAction> in FrontendAction.cpp.

- Plugins don't need to export _ZN4llvm8Registry*.
  - Win32.DLL cannot merge common symbols among DLLs. Static members in llvm::Registry should be instantiated in a parent.

llvm-svn: 212821

clang/examples/PrintFunctionNames/PrintFunctionNames.exports

@@ -1 +0,0 @@
-_ZN4llvm8Registry*

clang/include/clang/Frontend/FrontendPluginRegistry.h

@@ -13,6 +13,9 @@
 #include "clang/Frontend/FrontendAction.h"
 #include "llvm/Support/Registry.h"
 
+// Instantiated in FrontendAction.cpp.
+extern template class llvm::Registry<clang::PluginASTAction>;
+
 namespace clang {
 
 /// The frontend plugin registry.

clang/lib/Frontend/FrontendAction.cpp

@@ -32,6 +32,8 @@
 #include <system_error>
 using namespace clang;
 
+template class llvm::Registry<clang::PluginASTAction>;
+
 namespace {
 
 class DelegatingDeserializationListener : public ASTDeserializationListener {