ecc_j_to_a interface change, optionally reduce x mod q.

ChangeLog

ecc-ecdsa-sign.c

ecc-ecdsa-verify.c

ecc-j-to-a.c

ecc-point-mul-g.c

ecc-point-mul.c

ecc.h

ecdsa-keygen.c

testsuite/ecc-mul-a-test.c

testsuite/ecc-mul-g-test.c

testsuite/testutils.c