Move target-specific logic out of generic MCAssembler.

Whether a fixup needs relaxation for the associated instruction is a
target-specific function, as the FIXME indicated. Create a hook for that
and use it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145881 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp b/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
index 9f2fd6d..12e0b3d 100644
--- a/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
+++ b/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
@@ -93,6 +93,15 @@
     // FIXME.
     return false;
   }
+
+  bool fixupNeedsRelaxation(const MCFixup &Fixup,
+                            uint64_t Value,
+                            const MCInstFragment *DF,
+                            const MCAsmLayout &Layout) const {
+    // FIXME.
+    assert(0 && "RelaxInstruction() unimplemented");
+  }
+
   
   void RelaxInstruction(const MCInst &Inst, MCInst &Res) const {
     // FIXME.