www/libmicrohttpd: Update to 0.9.75
- Correct license declaration.
- Remove libgcrypt dependency. Neither MHD nor GnuTLS needs it.
- Enforce configure to use libcurl if TESTCURL is enabled.
PR: 260777
Reported by: Evgeny Grin (co-maintainer of GNU libmicrohttpd, via mail)