[MC][PowerPC] Fix a crash when redefining a symbol after .set

Fix PR44284. This is probably not valid assembly but we should not crash.

Reviewed By: luporl, #powerpc, steven.zhang

Differential Revision: https://reviews.llvm.org/D71443

llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp

@@ -201,7 +201,8 @@ public:
 
   void finish() override {
     for (auto *Sym : UpdateOther)
-      copyLocalEntry(Sym, Sym->getVariableValue());
+      if (Sym->isVariable())
+        copyLocalEntry(Sym, Sym->getVariableValue());
   }
 
 private:

llvm/test/MC/PowerPC/ppc64-localentry-symbols.s

@@ -32,3 +32,8 @@ func:
   nop
   nop
   .localentry func, 8
+
+## PR44284 Don't crash if err is redefined after .set
+.set err, _err
+.globl err
+err: