Fix automake to help compilation on FreeBSD

[xbeaudouin]

Hi !

I have updated the automake stuff to add :

• dependency on Judy unless it will not compile
• dependency on libexecinfo that implement backtrace stuff needed by your software.

Here is the diff against configure.ac to add this :
diff -u --recursive pcaputils.orig/configure.ac pcaputils/configure.ac
--- pcaputils.orig/configure.ac 2012-07-09 16:45:25.000000000 +0200
+++ pcaputils/configure.ac 2012-07-09 18:04:52.000000000 +0200
@@ -14,10 +14,13 @@
AC_SUBST([EXTRA_CFLAGS])

Checks for libraries.

+AC_SEARCH_LIBS([JudyLGet], [Judy], [], [AC_MSG_ERROR([Cannot find libJudy])])
+AC_SEARCH_LIBS([backtrace], [execinfo])

Checks for header files.

AC_CHECK_HEADERS([fcntl.h inttypes.h netdb.h netinet/in.h stdint.h stdlib.h string.h sys/param.h sys/socket.h sys/time.h syslog.h unistd.h], [], [AC_MSG_ERROR([required header not found])])
AC_CHECK_HEADERS([endian.h sys/endian.h execinfo.h])
+AC_CHECK_HEADERS([Judy.h])

Checks for typedefs, structures, and compiler characteristics.

AC_HEADER_STDBOOL

Regards