gst/multipart/multipartmux.c: Push header in a separate buffer instead of memcpy...

gst/multipart/multipartmux.c: Push header in a separate buffer instead of memcpy:ing all data

Original commit message from CVS:
Patch by: Jonas Holmberg <jonas dot holmberg at axis dot com>
* gst/multipart/multipartmux.c: (gst_multipart_mux_collected):
Push header in a separate buffer instead of memcpy:ing all data
Change LF => CRLF in headers
Move trailing LF to header