Remove all of the NEED_SHORT_EXTERNAL_NAMES stuff. There is scant information availa...

Remove all of the NEED_SHORT_EXTERNAL_NAMES stuff.  There is scant information available as to which linkers ever had a 15-character global symbol name limit.  AFAICT, it might have been a VMS and/or a.out BSD thing, but none of those platforms have ever been supported by libjpeg-turbo (nor are such systems supported by other open source libraries of this nature.)

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1307 632fc199-4ca6-4c93-a231-07263d6284db