windows.cfg: Add GetDlgItem() (#1921)

Reference:
https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-getdlgitem

cfg/windows.cfg

@@ -5889,6 +5889,22 @@ HFONT CreateFont(
       <not-uninit/>
     </arg>
   </function>
+  <!-- HWND GetDlgItem(
+  _In_opt_ HWND hDlg,
+  _In_ int nIDDlgItem); -->
+  <function name="GetDlgItem">
+    <noreturn>false</noreturn>
+    <returnValue type="HWND"/>
+    <use-retval/>
+    <leak-ignore/>
+    <arg nr="1" direction="in">
+      <not-uninit/>
+    </arg>
+    <arg nr="2" direction="in">
+      <not-uninit/>
+      <not-bool/>
+    </arg>
+  </function>
   <podtype name="POINTER_SIGNED" sign="s"/>
   <podtype name="POINTER_UNSIGNED" sign="u"/>
   <podtype name="__time32_t" sign="s" size="4"/>