Add basic fuzzing support for libstrophe

configure.ac

@@ -33,6 +33,16 @@ AC_ARG_ENABLE([tls],
 AC_ARG_ENABLE([cares],
     [AS_HELP_STRING([--enable-cares], [use c-ares for DNS resolution])])
 
+AC_ARG_ENABLE([fuzzing], [--enable-fuzzing    Turn on fuzzing],
+	      [case "${enableval}" in yes) fuzzing=true ;; no)  fuzzing=false ;; *) AC_MSG_ERROR([bad value ${enableval} for --enable-fuzzing]) ;; esac],[fuzzing=false])
+AM_CONDITIONAL([FUZZ], [test x$fuzzing = xtrue])
+
+if test "x$enable_fuzzing" = "xyes" ; then
+	if ! test "x$CC" = "xclang" ; then
+		AC_MSG_ERROR(["You need to set CC=clang to use --enable-fuzzing, used $CC"])
+	fi
+fi
+
 AC_SEARCH_LIBS([socket], [network socket])
 AC_CHECK_FUNCS([snprintf vsnprintf])
 AC_CHECK_DECLS([va_copy], [], [], [#include <stdarg.h>])