Reduce test count for some of the slower tests.

ChangeLog

testsuite/ecc-mod-arith-test.c

testsuite/ecc-mod-test.c

testsuite/ecc-modinv-test.c

testsuite/ecc-mul-a-test.c

testsuite/ecc-redc-test.c

testsuite/ecc-sqrt-test.c

testsuite/eddsa-compress-test.c

testsuite/poly1305-test.c

testsuite/random-prime-test.c

testsuite/rsa-compute-root-test.c

testsuite/rsa-sec-decrypt-test.c