Add copy of opus library in deps/third_party.

opus/win32/genversion.bat

+@echo off
+
+setlocal enableextensions enabledelayedexpansion
+
+for /f %%v in ('git describe --tags --match "v*"') do set version=%%v
+
+if not "%version%"=="" goto :gotversion
+
+if exist "%~dp0..\version.mk" goto :getversion
+
+echo Git cannot be found, nor can version.mk. Generating unknown version.
+
+set version=unknown
+
+goto :gotversion
+
+:getversion
+
+for /f "delims== tokens=2" %%v in (%~dp0..\version.mk) do set version=%%v
+
+set version=!version:^"=!
+set version=!version: =!
+
+:gotversion
+
+set version_out=#define %2 "%version%"
+set version_mk=%2 = "%version%"
+
+echo %version_out%> %1_temp
+
+if %version%==unknown goto :skipgenerate
+
+echo # static version string; update manually every release.> "%~dp0..\version.mk"
+echo %version_mk%>> "%~dp0..\version.mk"
+
+:skipgenerate
+
+echo n | comp %1_temp %1 > NUL 2> NUL
+
+if not errorlevel 1 goto exit
+
+copy /y %1_temp %1
+
+:exit
+
+del %1_temp