sys/windows: add definitions

core/sys/windows/shell32.odin

@@ -6,4 +6,12 @@ foreign import shell32 "system:Shell32.lib"
 @(default_calling_convention="stdcall")
 foreign shell32 {
 	CommandLineToArgvW :: proc(cmd_list: wstring, num_args: ^c_int) -> ^wstring ---
+	ShellExecuteW :: proc(
+		hwnd: HWND,
+		lpOperation: LPCWSTR,
+		lpFile: LPCWSTR,
+		lpParameters: LPCWSTR,
+		lpDirectory: LPCWSTR,
+		nShowCmd: INT,
+	) -> HINSTANCE ---
 }