Remove the embedded sha1 code, and use one of botan or gcrypt

This adds a hard dependency on one of Botan or gcrypt. Botan is already a
recommended dependency, and gcrypt is probably packaged almost everywhere,
so this should not be a big deal.

ref #3241

louloulibs/louloulibs.h.cmake

@@ -3,6 +3,7 @@
 #cmakedefine SYSTEMD_FOUND
 #cmakedefine POLLER ${POLLER}
 #cmakedefine BOTAN_FOUND
+#cmakedefine GCRYPT_FOUND
 #cmakedefine UDNS_FOUND
 #cmakedefine SOFTWARE_VERSION "${SOFTWARE_VERSION}"
 #cmakedefine PROJECT_NAME "${PROJECT_NAME}"