instead of simply doing an assert when running out of memory in emem, throw a new...

instead of simply doing an assert when running out of memory in emem, throw a new OutOfMemoryError Exception, so file.c can show at least a better explanation to the user before Wireshark terminates

XXX - to prevent a busy wait, I need a portable way to wait for a short time period, like Sleep() for Windows

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@20437 f5534014-38df-0310-8fa8-9805f1628bb7