cli: honor -w/--no-warnings for the file-too-large skip message

Fixes #2137. `-w`/`--no-warnings` skips every other warning in `cli/yara.c` but not the "skipping X because it's larger than N bytes" message from `scan_dir`. That one's printed unconditionally on both the POSIX and Windows code paths, so `-w -z <size>` still spams stderr with a line per oversized file. Wrapped both prints in `if (!ignore_warnings)`, same flag and same pattern already used for the other warnings in this file (e.g. the `CALLBACK_MSG_TOO_SLOW_SCANNING` / `CALLBACK_MSG_TOO_MANY_MATCHES` cases). No behavior change to which files get scanned, just the message. Didn't have a build toolchain handy to test this on, but it's a one-line `else` -> `else if (!ignore_warnings)` in each of the two `scan_dir` implementations (Unix and Windows), matching the guard style already used three other times in this same file.