patch 8.0.1178: using old compiler on MS-Windows

Problem:    Using old compiler on MS-Windows.
Solution:   Switch default build on MS-Windows to use MSVC 2015. (Ken Takata)

src/msvc2015.bat

@@ -0,0 +1,33 @@
+@echo off
+rem To be used on MS-Windows for Visual C++ 2015 (either Express or Community)
+rem See INSTALLpc.txt for information.
+rem
+rem Usage:
+rem   For x86 builds run this without options:
+rem     msvc2015
+rem   For x64 builds run this with "x86_amd64" option:
+rem     msvc2015 x86_amd64
+@echo on
+
+call "%VS140COMNTOOLS%..\..\VC\vcvarsall.bat" %*
+
+rem Use Windows SDK 7.1A for targeting Windows XP.
+if "%ProgramFiles(x86)%"=="" (
+	set "WinSdk71=%ProgramFiles%\Microsoft SDKs\Windows\v7.1A"
+) else (
+	set "WinSdk71=%ProgramFiles(x86)%\Microsoft SDKs\Windows\v7.1A"
+)
+if not exist "%WinSdk71%" (
+	echo Windows SDK 7.1A is not found.  Targeting Windows Vista and later.
+	goto :eof
+)
+
+set INCLUDE=%WinSdk71%\Include;%INCLUDE%
+if "%Platform%"=="x64" (
+	set "LIB=%WinSdk71%\Lib\x64;%LIB%"
+	set SUBSYSTEM_VER=5.02
+) else (
+	set "LIB=%WinSdk71%\Lib;%LIB%"
+	set SUBSYSTEM_VER=5.01
+)
+set CL=/D_USING_V110_SDK71_