winmm/tests: Use the available ARRAY_SIZE() macro.

dlls/winmm/tests/joystick.c

@@ -139,7 +139,7 @@ static void test_api(void)
     /* Try some unusual period values for joySetCapture and unusual threshold values for joySetThreshold.
      * Windows XP allows almost all test values, Windows 8 will return error on most test values, Windows
      * 98 allows anything but cuts the values to their maximum supported values internally. */
-    for (i = 0; i < sizeof(period) / sizeof(period[0]); i++)
+    for (i = 0; i < ARRAY_SIZE(period); i++)
     {
         ret = joySetCapture(window, joyid, period[i], FALSE);
         if (win8 && ((1 << i) & period_win8_error))
@@ -190,7 +190,7 @@ static void test_api(void)
     ok(ret == JOYERR_NOERROR, "Expected %d, got %d\n", JOYERR_NOERROR, ret);
 
     infoex.ex.dwSize = sizeof(infoex.ex);
-    for (i = 0; i < sizeof(flags) / sizeof(flags[0]); i++)
+    for (i = 0; i < ARRAY_SIZE(flags); i++)
     {
         infoex.ex.dwFlags = flags[i];
         ret = joyGetPosEx(joyid, &infoex.ex);

dlls/winmm/tests/midi.c

@@ -549,7 +549,7 @@ static void CALLBACK time_stamp_callback(HMIDIOUT hmo, UINT msg, DWORD_PTR insta
     struct time_stamp_records *records = (struct time_stamp_records *)instance;
     switch (msg) {
     case MM_MOM_POSITIONCB:
-        if (records->count < sizeof(records->time_stamp)/sizeof(records->time_stamp[0]))
+        if (records->count < ARRAY_SIZE(records->time_stamp))
             records->time_stamp[records->count] = GetTickCount();
         records->count++;
         break;

dlls/winmm/tests/mmio.c

@@ -606,7 +606,7 @@ static LRESULT CALLBACK mmio_test_IOProc(LPSTR lpMMIOInfo, UINT uMessage, LPARAM
     case MMIOM_OPEN:
         if (lpInfo->fccIOProc == FOURCC_DOS)
             lpInfo->fccIOProc = mmioFOURCC('F', 'A', 'I', 'L');
-        for (i = 0; i < sizeof(lpInfo->adwInfo) / sizeof(*lpInfo->adwInfo); i++)
+        for (i = 0; i < ARRAY_SIZE(lpInfo->adwInfo); i++)
             ok(lpInfo->adwInfo[i] == 0, "[%d] Expected 0, got %u\n", i, lpInfo->adwInfo[i]);
         return MMSYSERR_NOERROR;
     case MMIOM_CLOSE: