proj4: Index-out-of-bounds in reverse_obs

Detailed report: https://oss-fuzz.com/testcase?key=6621912241274880 Project: proj4 Fuzzer: libFuzzerproj4standardfuzzer Fuzz target binary: standardfuzzer Job Type: libfuzzerubsanproj4 Platform Id: linux Crash Type: Index-out-of-bounds Crash Address: Crash State: reverseobs pjinvobs projtransobs...