[AsmPrinter] Hide implementation details

NFC.

llvm-svn: 241169
diff --git a/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h b/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h
index c66d141..a5b399f 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h
+++ b/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h
@@ -29,7 +29,7 @@
 
 namespace llvm {
 /// \brief Collects and handles line tables information in a CodeView format.
-class WinCodeViewLineTables : public AsmPrinterHandler {
+class LLVM_LIBRARY_VISIBILITY WinCodeViewLineTables : public AsmPrinterHandler {
   AsmPrinter *Asm;
   DebugLoc PrevInstLoc;