Port Midi gives compile warnings

[riban-bw]

Compiling portmidi 217 on Windows (and possibly other platforms) using MinGW64 gcc give several warnings:

Filename	Line	Warning
pmwin.c	94	warning: pointer targets in passing argument 5 of 'RegQueryValueExA' differ in signedness [-Wpointer-sign]
pmwin.c	94	warning: pointer targets in passing argument 6 of 'RegQueryValueExA' differ in signedness [-Wpointer-sign]
pmwinmm.c	184	warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
pmwinmm.c	224	warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
pmwinmm.c	551	warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
pmwinmm.c	645	warning: suggest parentheses around assignment used as truth value [-Wparentheses]
pmwinmm.c	648	warning: suggest parentheses around assignment used as truth value [-Wparentheses]
pmwinmm.c	675	warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
pmwinmm.c	691	warning: variable 'new_driver_time' set but not used [-Wunused-but-set-variable]
pmwinmm.c	720	warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
pmwinmm.c	674	warning: unused variable 'entry' [-Wunused-variable]
pmwinmm.c	831	warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
pmwinmm.c	894	warning: unused variable 'dur' [-Wunused-variable]
pmwinmm.c	1211	warning: assignment to 'uint32_t *' {aka 'unsigned int *'} from incompatible pointer type 'DWORD *' {aka 'long unsigned int *'} [-Wincompatible-pointer-types]
pmwinmm.c	1333	warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
pmwinmm.c	1335	warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
pmwinmm.c	1422	warning: unused variable 'doneAny' [-Wunused-variable]
pmwinmm.c	674	warning: 'entry' defined but not used [-Wunused-variable]

This may be due to migration to 64-bit compiler. Should check that these warnings won't have adverse affect and correct source code to remove warnings.