Log Message:
Update to texlive 2015.

pdfTEX: Support JPEG Exif as well as JFIF; do not even emit a warning if
 \pdfinclusionerrorlevel is negative; sync with xpdf 3.04.
LuaTEX: New library newtokenlib for scanning tokens; bug fixes in the normal
 random number generator and other places.
XeTEX: Image handling fixes; xdvipdfmx binary looked for first as a sibling
 to xetex; internal XDV opcodes changed.
MetaPost: New numbersystem binary; new Japanese-enabled upmpost and
 updvitomp programs, analogous to up*tex.
Infrastructure: The fmtutil script has been reimplemented to read
 fmtutil.cnf on a per-tree basis, analogous to updmap. Web2C mktex* scripts
 (including mktexlsr, mktextfm, mktexpk) now prefer programs in their own
 directory, instead of always using the existing PATH.