[configure] add configure support for PCRE Posix library
Debian tried unsuccessfully to build with libpcreposix. This adds proper
support to autoconf/configure.ac for it.
Based on the patch by C.J. Adams-Collier in bug #483.
bgpd/bgp_{regex,routemap}.h: Pull in PCRE POSIX header if available.
diff --git a/bgpd/bgp_routemap.c b/bgpd/bgp_routemap.c
index 4fff026..aa7dbce 100644
--- a/bgpd/bgp_routemap.c
+++ b/bgpd/bgp_routemap.c
@@ -28,11 +28,15 @@
#include "plist.h"
#include "memory.h"
#include "log.h"
-#ifdef HAVE_GNU_REGEX
-#include <regex.h>
+#ifdef HAVE_LIBPCREPOSIX
+# include <pcreposix.h>
#else
-#include "regex-gnu.h"
-#endif /* HAVE_GNU_REGEX */
+# ifdef HAVE_GNU_REGEX
+# include <regex.h>
+# else
+# include "regex-gnu.h"
+# endif /* HAVE_GNU_REGEX */
+#endif /* HAVE_LIBPCREPOSIX */
#include "buffer.h"
#include "sockunion.h"