win,nfc: use #pragma warnings() for MSVC only

PR-URL: https://github.com/libuv/libuv/pull/2854
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Bartosz Sosnowski <bartosz@janeasystems.com>
Reviewed-By: Jameson Nash <vtjnash@gmail.com>
Co-authored-by: Anna Henningsen <github@addaleax.net>

src/win/util.c

@@ -1806,7 +1806,9 @@ int uv_os_uname(uv_utsname_t* buffer) {
     pRtlGetVersion(&os_info);
   } else {
     /* Silence GetVersionEx() deprecation warning. */
+    #ifdef _MSC_VER
     #pragma warning(suppress : 4996)
+    #endif
     if (GetVersionExW(&os_info) == 0) {
       r = uv_translate_sys_error(GetLastError());
       goto error;