CONFIGURE: Inform about optional build dependencies Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>

BUILD: Fall back to non-strict http parser, if strict is not available Some platforms (like Debian), don't ship http-parser-strict at all, but only the non-strict variant. Fall back to the non-strict library if the strict variant is not found. Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>

Secrets: m4 macros for jansson and http-parser Prepares autoconf for the new Secrets Provider dependencies Related: https://fedorahosted.org/sssd/ticket/2913 Signed-off-by: Christian Heimes <cheimes@redhat.com> Reviewed-by: Simo Sorce <simo@redhat.com>