configure.ac : Detect the size of off_t.
diff --git a/configure.ac b/configure.ac
index 84b33fc..8b6edcb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -40,6 +40,7 @@
 AC_SYS_LARGEFILE
 AC_FUNC_FSEEKO
 
+AC_CHECK_SIZEOF(off_t,1)	# Fake default value.
 AC_CHECK_SIZEOF([void*])
 AC_SEARCH_LIBS([lround],[m], [AC_DEFINE(HAVE_LROUND,1,lround support)])