URLs: change http to https in many places

docs/INSTALL

docs/LICENSE-MIXING

docs/libcurl/opts/CURLOPT_TFTP_NO_OPTIONS.3

lib/curl_ntlm_core.c

lib/curl_ntlm_wb.c

lib/http_ntlm.c

lib/vauth/cleartext.c

lib/vauth/cram.c

lib/vauth/digest.c

lib/vauth/digest.h

lib/vauth/digest_sspi.c

lib/vauth/krb5_sspi.c

lib/vauth/ntlm.c

lib/vauth/oauth2.c

lib/vauth/spnego_gssapi.c

lib/vauth/spnego_sspi.c

lib/vauth/vauth.c

lib/vauth/vauth.h

winbuild/Makefile.vc