Add additional protections against defining INT32 if another header has already defined it (code borrowed from libjpeg v8.)  This isn't necessary when using the libjpeg-turbo build system on Windows, because the CMake generated jconfig.h defines INT32 and then defines XMD_H to trick jmorecfg.h into not redefining it.  However, some projects build libjpeg-turbo using their own build systems.


git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.4.x@1593 632fc199-4ca6-4c93-a231-07263d6284db