[Arm] Fix UAF in ARMConstantIslandPass (#146232)

#146198 changes
```
    for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i)
      BRChange |= fixupImmediateBr(ImmBranches[i]);
```
to
```
    for (ImmBranch &Br : ImmBranches)
      BRChange |= fixupImmediateBr(Br);
```
Unfortunately, they are not NFC and cause the buildbot error. e.g.,
https://lab.llvm.org/buildbot/#/builders/24/builds/9943
https://lab.llvm.org/buildbot/#/builders/169/builds/12570
Use make_early_inc_range to fix the issue

Author: qinkunbao

llvm/lib/Target/ARM/ARMConstantIslandPass.cpp

@@ -476,7 +476,7 @@ bool ARMConstantIslands::runOnMachineFunction(MachineFunction &mf) {
 
     LLVM_DEBUG(dbgs() << "Beginning BR iteration #" << NoBRIters << '\n');
     bool BRChange = false;
-    for (ImmBranch &Br : ImmBranches)
+    for (ImmBranch &Br : llvm::make_early_inc_range(ImmBranches))
       BRChange |= fixupImmediateBr(Br);
     if (BRChange && ++NoBRIters > 30)
       report_fatal_error("Branch Fix Up pass failed to converge!");