SDL_test: use SDLCALL calling convention

This is needed when using a pre-built static SDL3_test library.

test/testautomation_time.c

@@ -13,7 +13,7 @@
 /**
  * Call to SDL_GetRealtimeClock
  */
-static int time_getRealtimeClock(void *arg)
+static int SDLCALL time_getRealtimeClock(void *arg)
 {
     int result;
     SDL_Time ticks;
@@ -28,7 +28,7 @@ static int time_getRealtimeClock(void *arg)
 /**
  * Test bidirectional SDL_DateTime conversions.
  */
-static int time_dateTimeConversion(void *arg)
+static int SDLCALL time_dateTimeConversion(void *arg)
 {
     int result;
     SDL_Time ticks[2];
@@ -103,7 +103,7 @@ static int time_dateTimeConversion(void *arg)
 /**
  * Test time utility functions.
  */
-static int time_dateTimeUtilities(void *arg)
+static int SDLCALL time_dateTimeUtilities(void *arg)
 {
     int result;