[MC] Remove duplicate getFixupKindInfo calls. NFC

Due to 8728e09
(`std::unique_ptr<MCAsmBackend> Backend`), the compiler doesn't know
that `Backend` will not be modified across function calls.

Author: MaskRay

llvm/lib/MC/MCAssembler.cpp

@@ -167,18 +167,12 @@ bool MCAssembler::evaluateFixup(const MCFixup &Fixup, const MCFragment *DF,
     }
   }
 
-  assert(getBackendPtr() && "Expected assembler backend");
-  bool IsTarget = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags &
-                  MCFixupKindInfo::FKF_IsTarget;
-
-  if (IsTarget)
+  unsigned FixupFlags = getBackend().getFixupKindInfo(Fixup.getKind()).Flags;
+  if (FixupFlags & MCFixupKindInfo::FKF_IsTarget)
     return getBackend().evaluateTargetFixup(*this, Fixup, DF, Target, STI,
                                             Value, WasForced);
 
-  unsigned FixupFlags = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags;
-  bool IsPCRel = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags &
-                 MCFixupKindInfo::FKF_IsPCRel;
-
+  bool IsPCRel = FixupFlags & MCFixupKindInfo::FKF_IsPCRel;
   bool IsResolved = false;
   if (IsPCRel) {
     if (Target.getSymB()) {
@@ -213,8 +207,7 @@ bool MCAssembler::evaluateFixup(const MCFixup &Fixup, const MCFragment *DF,
       Value -= getSymbolOffset(Sym);
   }
 
-  bool ShouldAlignPC = getBackend().getFixupKindInfo(Fixup.getKind()).Flags &
-                       MCFixupKindInfo::FKF_IsAlignedDownTo32Bits;
+  bool ShouldAlignPC = FixupFlags & MCFixupKindInfo::FKF_IsAlignedDownTo32Bits;
   assert((ShouldAlignPC ? IsPCRel : true) &&
     "FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!");