More prefer SDL_zero*()

Transform clearing of arrays into SDL_zeroa(), and
clearing through a T* with size(T) into SDL_zerop().

Extends commit 83fb7b6636.

src/power/haiku/SDL_syspower.c

@@ -56,7 +56,7 @@ bool SDL_GetPowerInfo_Haiku(SDL_PowerState *state, int *seconds, int *percent)
         return false; // maybe some other method will work?
     }
 
-    SDL_memset(regs, '\0', sizeof(regs));
+    SDL_zeroa(regs);
     regs[0] = APM_FUNC_OFFSET + APM_FUNC_GET_POWER_STATUS;
     regs[1] = APM_DEVICE_ALL;
     rc = ioctl(fd, APM_BIOS_CALL, regs);