headers: Add IsUserCetAvailableInEnvironment in sysinfoapi.h

Required for https://github.com/mozilla/gecko-dev/commit/cc73dd0338135e9fee7adddb9981515c8e3714ca

Signed-off-by: Biswapriyo Nath <nathbappai@gmail.com>
Signed-off-by: LIU Hao <lh_mouse@126.com>
diff --git a/mingw-w64-headers/include/sysinfoapi.h b/mingw-w64-headers/include/sysinfoapi.h
index dfacf62..ef4537f 100644
--- a/mingw-w64-headers/include/sysinfoapi.h
+++ b/mingw-w64-headers/include/sysinfoapi.h
@@ -41,8 +41,18 @@
 #if _WIN32_WINNT >= 0x0600
   WINBASEAPI ULONGLONG WINAPI GetTickCount64 (VOID);
 #endif
+
+#define USER_CET_ENVIRONMENT_WIN32_PROCESS 0x00000000
+#define USER_CET_ENVIRONMENT_SGX2_ENCLAVE 0x00000002
+#define USER_CET_ENVIRONMENT_VBS_ENCLAVE 0x00000010
+#define USER_CET_ENVIRONMENT_VBS_BASIC_ENCLAVE 0x00000011
+
+#if (NTDDI_VERSION >= NTDDI_WIN10_VB)
+  WINBASEAPI WINBOOL WINAPI IsUserCetAvailableInEnvironment(DWORD UserCetEnvironment);
 #endif
 
+#endif /* WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP) */
+
 #if WINAPI_FAMILY_PARTITION (WINAPI_PARTITION_DESKTOP) || _WIN32_WINNT >= _WIN32_WINNT_WIN10
 
   typedef struct _MEMORYSTATUSEX {