Added support for fstatvfs.

diff --git a/configure.ac b/configure.ac
index 76675f8..328ac83 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1025,6 +1025,8 @@
 	clone \
 	finite \
 	fpclass \
+	fstatfs \
+	fstatvfs \
 	ftruncate \
 	ftruncate64 \
 	futimes \