icu: Heap-buffer-overflow in utext_previous32_58

Project: https://github.com/unicode-org/icu.git Detailed report: https://clusterfuzz-external.appspot.com/testcase?key=5560648738013184 Project: icu Fuzzer: libFuzzericuucasemapfuzzer Fuzz target binary: ucasemapfuzzer Job Type: libfuzzerasanicu Platform Id: linux Crash Type: Heap-buffer-overflow...