[hwasan] Replace &LI with *LI, to fix build breakage

My patch (https://github.com/llvm/llvm-project/commit/b3b6edefdb7ae77e4b2344c9a64fd1d486c91405) broke the build
(https://lab.llvm.org/buildbot/#/builders/5/builds/37053) because it incorrectly assumed LoopInfo could not be null
and used a reference. This fixes forward by replacing &LI with *LI.