win32: remove check for SetPriorityClass()

This function is always available, which is reflected by the fact that
the configure check doesn't actually bother to check for its existence.
Instead, MinGW and Cygwin imply it. The check was probably "needed" when
the priority code was still in a separate source file.

Remove the check, and use _WIN32 for testing for the win32 API (in a
bunch of other places too).

options/options.c

@@ -29,7 +29,7 @@
 
 #include "config.h"
 
-#if HAVE_PRIORITY
+#ifdef _WIN32
 #include <windows.h>
 #endif
 
@@ -111,7 +111,7 @@ const m_option_t mp_opts[] = {
     OPT_FLAG("msg-color", msg_color, CONF_GLOBAL | CONF_PRE_PARSE),
     OPT_FLAG("msg-module", msg_module, CONF_GLOBAL),
     OPT_FLAG("msg-time", msg_time, CONF_GLOBAL),
-#if HAVE_PRIORITY
+#ifdef _WIN32
     OPT_CHOICE("priority", w32_priority, 0,
                ({"no",          0},
                 {"realtime",    REALTIME_PRIORITY_CLASS},

player/main.c

@@ -63,7 +63,7 @@
 #include "command.h"
 #include "screenshot.h"
 
-#if defined(__MINGW32__) || defined(__CYGWIN__)
+#ifdef _WIN32
 #include <windows.h>
 
 #ifndef BASE_SEARCH_PATH_ENABLE_SAFE_SEARCHMODE
@@ -287,7 +287,7 @@ static void osdep_preinit(int *p_argc, char ***p_argv)
     mp_get_converted_argv(p_argc, p_argv);
 #endif
 
-#if defined(__MINGW32__) || defined(__CYGWIN__)
+#ifdef _WIN32
     // stop Windows from showing all kinds of annoying error dialogs
     SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX);
 
@@ -525,7 +525,7 @@ int mpv_main(int argc, char *argv[])
         exit_player(mpctx, EXIT_NONE);
     }
 
-#if HAVE_PRIORITY
+#ifdef _WIN32
     if (opts->w32_priority > 0)
         SetPriorityClass(GetCurrentProcess(), opts->w32_priority);
 #endif

wscript

@@ -185,11 +185,6 @@ iconv support use --disable-iconv.",
         'desc': 'w32/dos paths',
         'deps_any': [ 'os-win32', 'os-cygwin' ],
         'func': check_true
-    }, {
-        'name': 'priority',
-        'desc': 'w32 priority API',
-        'deps_any': [ 'os-win32', 'os-cygwin'],
-        'func': check_true
     }, {
         'name': '--waio',
         'desc': 'libwaio for win32',