In the Windows installer packages, place a duplicate copy of turbojpeg.dll in c:...

In the Windows installer packages, place a duplicate copy of turbojpeg.dll in c:\libjpeg-turbo[-gcc][64]\bin.  This is mainly to give installers an easy way to find the DLL for the purposes of bundling it.  Specifically, this was necessary for TurboVNC, becuase 32-bit CMake running on 64-bit Windows cannot ever access the "real" c:\windows\system32 directory.

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1027 632fc199-4ca6-4c93-a231-07263d6284db