Switch MSVC and console build scripts to rolling releases.

src/msvcbuild.bat

@@ -42,6 +42,9 @@ if exist minilua.exe.manifest^
 minilua %DASM% -LN %DASMFLAGS% -o host\buildvm_arch.h vm_x86.dasc
 @if errorlevel 1 goto :BAD
 
+git show -s --format=%ct >luajit_relver.txt
+minilua host\genversion.lua
+
 %LJCOMPILE% /I "." /I %DASMDIR% host\buildvm*.c
 @if errorlevel 1 goto :BAD
 %LJLINK% /out:buildvm.exe buildvm*.obj