Define and use new TMP_GMP_ALLOC macro.

ChangeLog

bignum-next-prime.c

bignum-random.c

gmp-glue.c

gmp-glue.h

pkcs1-decrypt.c

pkcs1-encrypt.c

pkcs1-rsa-digest.c

pkcs1-rsa-md5.c

pkcs1-rsa-sha1.c

pkcs1-rsa-sha256.c

pkcs1-rsa-sha512.c