autoconf: use XORG_DEFAULT_OPTIONS

autoconf: use XORG_DEFAULT_OPTIONS

XCB has been part of X.Org for a while now. This patch will harmonize the XCB
configuration, using xorg-macros series of macros. It is already used in the
XCB utils packages and is needed to build xcb-proto.

The XORG_DEFAULT_OPTIONS already includes the statement for the silent
rules.

The AC_PROG_CC statement is removed so as not to override AC_PROG_CC_C99
in XORG_DEFAULT_OPTIONS. The effective change is that xcb now uses c99 as
requested.

Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Gaetan Nadon <memsize@videotron.ca>