Convert a few more comparisons to isPositionIndependent(). NFC.

llvm-svn: 273945
diff --git a/llvm/lib/Target/X86/X86Subtarget.h b/llvm/lib/Target/X86/X86Subtarget.h
index c3967c4..a274b79 100644
--- a/llvm/lib/Target/X86/X86Subtarget.h
+++ b/llvm/lib/Target/X86/X86Subtarget.h
@@ -523,9 +523,7 @@
     return PICStyle == PICStyles::StubPIC;
   }
 
-  bool isPositionIndependent() const {
-    return TM.getRelocationModel() == Reloc::PIC_;
-  }
+  bool isPositionIndependent() const { return TM.isPositionIndependent(); }
 
   bool isCallingConvWin64(CallingConv::ID CC) const {
     switch (CC) {