Change --enable-pedantic to use -std=c99 and not -ansi (C90).

Change --enable-pedantic to use -std=c99 and not -ansi (C90).

There's quite a bit of our code that fails compilation with
"gcc -pedantic -ansi" and should not be changed - like, LZ4 using
"long long" variables which C90 does not have.  Be pragmatic.

trac #616

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1465477232-25826-1-git-send-email-gert@greenie.muc.de>
URL: http://article.gmane.org/gmane.network.openvpn.devel/11882
Signed-off-by: Gert Doering <gert@greenie.muc.de>