windows.cfg: Added support for '_isatty()'

Author: orbitcowboy

cfg/windows.cfg

@@ -4431,6 +4431,18 @@ HFONT CreateFont(
       <not-bool/>
     </arg>
   </function>
+  <!-- int _isatty(int fd); -->
+  <function name="_isatty">
+    <use-retval/>
+    <returnValue type="int"/>
+    <noreturn>false</noreturn>
+    <leak-ignore/>
+    <arg nr="1">
+      <valid>0:</valid>
+      <not-uninit/>
+      <not-bool/>
+    </arg>
+  </function>
   <!--VOID WINAPI FreeLibraryAndExitThread(
   _In_ HMODULE hModule,
   _In_ DWORD   dwExitCode);-->