+if test "x$with_libperl" = "xyes"
+then
+ SAVE_CFLAGS=$CFLAGS
+ SAVE_LDFLAGS=$LDFLAGS
+ CFLAGS="$CFLAGS $PERL_CFLAGS"
+ LDFLAGS="$LDFLAGS $PERL_LDFLAGS"
+
+ AC_CACHE_CHECK([if perl supports ithreads],
+ [have_perl_ithreads],
+ AC_LINK_IFELSE(
+ AC_LANG_PROGRAM(
+ [[
+#include <EXTERN.h>
+#include <perl.h>
+#include <XSUB.h>
+
+#if !defined(USE_ITHREADS)
+# error "Perl does not support ithreads!"
+#endif /* !defined(USE_ITHREADS) */
+ ]],
+ [[ ]]),
+ [have_perl_ithreads="yes"],
+ [have_perl_ithreads="no"]
+ )
+ )
+
+ if test "x$have_perl_ithreads" = "xyes"
+ then
+ AC_DEFINE(HAVE_PERL_ITHREADS, 1, [Define if Perl supports ithreads.])
+ fi
+
+ CFLAGS=$SAVE_CFLAGS
+ LDFLAGS=$SAVE_LDFLAGS
+fi
+