[PATCH:xhost] Add AC_USE_SYSTEM_EXTENSIONS to expose non-standard extensions

[Alan Coopersmith]

Required on Solaris to expose definitions in system headers that
are not defined in the XPG standards now that xtrans 1.3 defines
_XOPEN_SOURCE to 600 on Solaris.

Fixes build failures:
In file included from /usr/include/rpc/rpcb_clnt.h:34:0,
                 from /usr/include/rpc/rpc.h:49,
                 from xhost.c:98:
/usr/include/rpc/rpcb_prot.h:159:3: error: unknown type name ‘u_int’
/usr/include/rpc/rpcb_prot.h:195:3: error: unknown type name ‘u_int’
/usr/include/rpc/rpcb_prot.h:223:2: error: unknown type name ‘u_int’
/usr/include/rpc/rpcb_prot.h:476:1: error: unknown type name ‘u_int’
/usr/include/rpc/rpcb_prot.h:489:1: error: unknown type name ‘u_int’

xhost.c: In function ‘change_host’:
xhost.c:554:11: error: ‘INET6_ADDRSTRLEN’ undeclared (first use in this function)
xhost.c:554:11: note: each undeclared identifier is reported only once for each function it appears in

xhost.c: In function ‘get_hostname’:
xhost.c:665:23: error: ‘NI_MAXHOST’ undeclared (first use in this function)

Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
---
 configure.ac |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/configure.ac b/configure.ac
index 0d6f506..4ec4de0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -11,6 +11,11 @@ AC_CONFIG_HEADERS([config.h])
 AM_INIT_AUTOMAKE([foreign dist-bzip2])
 AM_MAINTAINER_MODE
 
+# Set common system defines for POSIX extensions, such as _GNU_SOURCE
+# Must be called before any macros that run the compiler (like
+# XORG_DEFAULT_OPTIONS) to avoid autoconf errors.
+AC_USE_SYSTEM_EXTENSIONS
+
 # Require X.Org macros 1.8 or later for MAN_SUBSTS set by XORG_MANPAGE_SECTIONS
 m4_ifndef([XORG_MACROS_VERSION],
 	  [m4_fatal([must install xorg-macros 1.8 or later before running autoconf/autogen])])
-- 
1.7.9.2