Restructure the propagation of -fPIC/-fPIE.

The PIC and PIE levels are not independent. In fact, if PIE is defined
it is always the same as PIC.

This is clear in the driver where ParsePICArgs returns a PIC level and
a IsPIE boolean. Unfortunately that is currently lost and we pass two
redundant levels down the pipeline.

This patch keeps a bool and a PIC level all the way down to codegen.

llvm-svn: 273566
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 27ef59a..6b93c69 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -873,10 +873,10 @@
   if (unsigned PICLevel = LangOpts.PICLevel) {
     Builder.defineMacro("__PIC__", Twine(PICLevel));
     Builder.defineMacro("__pic__", Twine(PICLevel));
-  }
-  if (unsigned PIELevel = LangOpts.PIELevel) {
-    Builder.defineMacro("__PIE__", Twine(PIELevel));
-    Builder.defineMacro("__pie__", Twine(PIELevel));
+    if (LangOpts.PIE) {
+      Builder.defineMacro("__PIE__", Twine(PICLevel));
+      Builder.defineMacro("__pie__", Twine(PICLevel));
+    }
   }
 
   // Macros to control C99 numerics and <float.h>