pass clang-ubsan, all 4 in fread.c (#4624)
pass clang-ubsan, all 4 in fread.c (#4624)


vlulla/data.table,Rdatatable/data.table,Rdatatable/data.table,Rdatatable/data.table,vlulla/data.table,jangorecki/data.table,Rdatatable/data.table,jangorecki/data.table,vlulla/data.table,vlulla/data.table,jangorecki/data.table,jangorecki/data.table