[Driver] x86-64 Windows is always PIC

This fixes PR23963.

llvm-svn: 240902
diff --git a/clang/lib/Driver/ToolChains.cpp b/clang/lib/Driver/ToolChains.cpp
index 27bc357..df74b41 100644
--- a/clang/lib/Driver/ToolChains.cpp
+++ b/clang/lib/Driver/ToolChains.cpp
@@ -2021,11 +2021,15 @@
   return getArch() == llvm::Triple::x86_64;
 }
 
-bool Generic_GCC::isPICDefault() const { return false; }
+bool Generic_GCC::isPICDefault() const {
+  return getArch() == llvm::Triple::x86_64 && getTriple().isOSWindows();
+}
 
 bool Generic_GCC::isPIEDefault() const { return false; }
 
-bool Generic_GCC::isPICDefaultForced() const { return false; }
+bool Generic_GCC::isPICDefaultForced() const {
+  return getArch() == llvm::Triple::x86_64 && getTriple().isOSWindows();
+}
 
 bool Generic_GCC::IsIntegratedAssemblerDefault() const {
   switch (getTriple().getArch()) {