Fix build on WinRT

There is no environment (like WinCE) and the basic version
of InitializeCriticalSection is unsupported.

https://codereview.qt-project.org/#/c/92496/

src/hb-mutex-private.hh

@@ -47,7 +47,11 @@
 #include <windows.h>
 typedef CRITICAL_SECTION hb_mutex_impl_t;
 #define HB_MUTEX_IMPL_INIT	{0}
+#if defined(WINAPI_FAMILY) && (WINAPI_FAMILY==WINAPI_FAMILY_PC_APP || WINAPI_FAMILY==WINAPI_FAMILY_PHONE_APP)
+#define hb_mutex_impl_init(M)	InitializeCriticalSectionEx (M, 0, 0)
+#else
 #define hb_mutex_impl_init(M)	InitializeCriticalSection (M)
+#endif
 #define hb_mutex_impl_lock(M)	EnterCriticalSection (M)
 #define hb_mutex_impl_unlock(M)	LeaveCriticalSection (M)
 #define hb_mutex_impl_finish(M)	DeleteCriticalSection (M)

src/hb-private.hh

@@ -142,6 +142,8 @@
 #define getenv(Name) NULL
 #define setlocale(Category, Locale) "C"
 static int errno = 0; /* Use something better? */
+#elif defined(WINAPI_FAMILY) && (WINAPI_FAMILY==WINAPI_FAMILY_PC_APP || WINAPI_FAMILY==WINAPI_FAMILY_PHONE_APP)
+#define getenv(Name) NULL
 #endif
 
 #if HAVE_ATEXIT