Add missing SRC variable

This is the only Makefile without SRC defined. This change enables a
standard Makefile include directive to cover crypto/jpake/*.d files.

This was automatically applied by AddSrcVarIfNeeded() in:
https://code.google.com/p/mike-bland/source/browse/openssl/update_makefiles.py



Change-Id: I030204a1bc873b5de5b06c8ddc0b94bb224c6650
Signed-off-by: Mike Bland <mbland@acm.org>
Signed-off-by: Geoff Thorpe <geoff@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>