[od] add libmodplug patches

These are patches for libmodplug that fix various UB issues.
They come from these PRs to the upstream repository:
1. Konstanty/libmodplug#92
2. Konstanty/libmodplug#93

The upstream maintainer has not merged any PRs in over a year.

Fixes #105.

Signed-off-by: Gleb Mazovetskiy <glex.spb@gmail.com>

Author: glebm