msvcrt: Add private define and header tests for _set_error_mode options.

dlls/msvcrt/msvcrt.h

@@ -568,6 +568,8 @@ struct MSVCRT__stat64 {
 #define MSVCRT__USEDENTRY      1
 
 #define MSVCRT__OUT_TO_DEFAULT 0
+#define MSVCRT__OUT_TO_STDERR  1
+#define MSVCRT__OUT_TO_MSGBOX  2
 #define MSVCRT__REPORT_ERRMODE 3
 
 /* ASCII char classification table - binary compatible */

dlls/msvcrt/tests/headers.c

@@ -340,6 +340,8 @@ static void test_defines(void)
     CHECK_DEF(_FREEENTRY);
     CHECK_DEF(_USEDENTRY);
     CHECK_DEF(_OUT_TO_DEFAULT);
+    CHECK_DEF(_OUT_TO_STDERR);
+    CHECK_DEF(_OUT_TO_MSGBOX);
     CHECK_DEF(_REPORT_ERRMODE);
     CHECK_DEF(_UPPER);
     CHECK_DEF(_LOWER);