hmac: Use xtrymalloc.
* src/hmac256.c (_gcry_hmac256_new): Use xtrymalloc. (_gcry_hmac256_file): Likewise.
Don't require config.h but stdint.h for STANDALONE.
Drop STANDALONE support for WindowsCE.
- GnuPG-bug-id: T3877
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>