convert: make apply_filter() adhere to standard Git error handling
apply_filter() returns a boolean that tells the caller if it
"did convert or did not convert". The variable `ret` was used throughout
the function to track errors whereas `1` denoted success and `0`
failure. This is unusual for the Git source where `0` denotes success.
Rename the variable and flip its value to make the function easier
readable for Git developers.
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>