Add if-no-present action for jsv8inc arg
diff --git a/configure.ac b/configure.ac
index 7b5b54c..833cb37 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1550,7 +1550,7 @@
# check for include files
AC_MSG_CHECKING(for V8 Javascript v8.h)
- AC_ARG_WITH(jsv8inc, [ --with-jsv8inc=path Set location of Javascript v8 include directory], [JSV8INCDIR="$withval"])
+ AC_ARG_WITH(jsv8inc, [ --with-jsv8inc=path Set location of Javascript v8 include directory], [JSV8INCDIR="$withval"], [JSV8INCDIR=])
# if not include dir is specified we try to find
if test -z "$JSV8INCDIR"; then