[asan] replace the flag uar_stack_size_log with two flags min_uar_stack_size_log/max_uar_stack_size_log

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@197370 91177308-0d34-0410-b5e6-96231b3b80d8
[asan] fix the test so that it works even if stack size is unlimited by default

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@197372 91177308-0d34-0410-b5e6-96231b3b80d8