tests/t-kdf: few changes to pthread example and fix win32/win64 builds
* src/gcrypt.h.in (gcry_kdf_thread_ops_t): New based on 'struct gcry_kdf_thread_ops'. (gcry_kdf_compute): Use 'gcry_kdf_thread_ops_t' instead of 'struct gcry_kdf_thread_ops'. * tests/Makefile.am: Define 't_kdf_LDADD' and 't_kdf_CFLAGS' on win32/win64 target too. * tests/t-kdf.c (pthread_jobs_launch_job): Set 'oldest_thread_idx' on first thread creation. (wait_all_jobs_completion): Reset 'oldest_thread_idx' to -1. (my_kdf_derive): Merge HAVE_PTHREAD ifdefs; Initialize 'oldest_thread_idx' to -1.
Windows build was not working because of missing HAVE_PTHREAD in
't-kdf.c' and LDADD/CFLAGS issue in 'Makefile.am'.
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>