mikmod: Upgrade mikmod core from v3.2.0 to v3.3.11

* Get rid of the non-functional GT2 loader
 * Add the UMX loader
 * Add HQ mixer routines (and make it configurable)
 * Allow samplerate to be configured at run/playtime
 * Support >64KHz mixing/playback
 * Correctly restore non-boost status

(The diff to upstream is much smaller now too!)

Change-Id: Iaa4ac901ba9cd4123bb225656976e78271353a72

apps/plugins/mikmod/SOURCES

@@ -5,7 +5,6 @@ load_asy.c
 load_dsm.c
 load_far.c
 load_gdm.c
-load_gt2.c
 load_imf.c
 load_it.c
 load_m15.c
@@ -17,6 +16,7 @@ load_s3m.c
 load_stm.c
 load_stx.c
 load_ult.c
+load_umx.c
 load_uni.c
 load_xm.c
 mdreg.c
@@ -34,6 +34,7 @@ sloader.c
 strdup.c
 strstr.c
 virtch.c
+virtch2.c
 virtch_common.c
 mikmod.c