mikmod (https://mikmod.sourceforge.net/)

Based on upstream commit 72424e1bebab470fbf8a2914dcd7903b742205e6
corresponding to mikmod 3.2.9 / libmikmod 3.3.12

Heavily customized for rockbox use:

 * converted most BOOL/INTs in function prototypes to 'int'
 * converted BOOL/INT in option enums to RB_BOOL / RB_INT
 * Silenced a _ton_ of "unused parameter" options
 * Custom player frontend that is fully i18n'd
 * Settings for mixer freq, quality, and other parameters
