Debug info: Get rid of the VLA indirection hack in FastISel.

Use the DIVariable::isIndirect() flag set by the frontend instead of
guessing whether to set the machine location's indirection bit.
Paired commit with CFE.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190961 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MachineLocation.h

@@ -44,7 +44,8 @@ public:
         Offset == Other.Offset;
   }
 
-  // Accessors
+  // Accessors.
+  /// \return true iff this is a register-indirect location.
   bool isIndirect()      const { return !IsRegister; }
   bool isReg()           const { return IsRegister; }
   unsigned getReg()      const { return Register; }