Use MSYS2 to build external libraries for Windows compile

build_scripts/Windows/env/env-msys2.bat

@@ -0,0 +1,39 @@
+:: Usage:
+:: call env-msys2.bat [reinstall|clean]
+
+:: Initialize environment
+call "%~dp0env.bat"
+if errorlevel 1 goto error_env
+
+rem openssl x86 doesn't compile with mingw64 x64
+:: Get gcc versions
+call "%ToolsPath%\get-gcc-version.bat" GCCVersion GCCArchitecture
+if "%GCCVersion%"=="" %cecho% error "Cannot get gcc version." & exit /B 1
+if "%GCCArchitecture%"=="" %cecho% error "Cannot get gcc architecture." & exit /B 1
+
+rem IF DEFINED ProgramFiles(x86) (
+if "%GCCArchitecture%"=="x64" (
+	:: x64
+	set MSYS2Architecture=x86_64
+	set MSYS2Base=64
+) else (
+	:: x86
+	set MSYS2Architecture=i686
+	set MSYS2Base=32
+)
+
+set EnvMSYS2Path=%EnvRootPath%\msys2
+
+call "%~dp0tools\prepare-msys2.bat" %1
+if errorlevel 1 exit /B %ERRORLEVEL%
+
+set EnvMSYS2SH=%EnvMSYS2Path%\msys%MSYS2Base%\usr\bin\sh.exe
+if not exist "%EnvMSYS2SH%" if errorlevel 1 goto error_env
+
+set EnvMSYS2Cmd="%EnvMSYS2SH%" -lc
+
+exit /B 0
+
+:error_env
+echo Failed to initialize environment.
+exit /B 1