fixed some autoreconf warnings

configure.ac

@@ -1299,7 +1299,6 @@ AC_MSG_NOTICE([checking types, headers, and functions])
 AC_CHECK_HEADERS([sys/param.h])
 AC_CHECK_HEADERS([libgen.h])
 #AC_CHECK_HEADERS([locale.h])
-AC_HEADER_STDC
 AC_CHECK_HEADERS([locale.h stdio.h stdarg.h fcntl.h malloc.h stdlib.h string.h strings.h unistd.h sys/stat.h getopt.h sys/time.h sys/types.h time.h dirent.h stdint.h ctype.h sys/xattr_h])
 
 # Do sys/resource.h separately
@@ -1454,7 +1453,7 @@ AC_SUBST(USEPLUGINS, [${enable_plugins}])
 
 AC_FUNC_ALLOCA
 AC_CHECK_DECLS([isnan, isinf, isfinite],,,[#include <math.h>])
-AC_STRUCT_ST_BLKSIZE
+AC_CHECK_MEMBERS([struct stat.st_blksize])
 UD_CHECK_IEEE
 AC_CHECK_TYPES([size_t, ssize_t, schar, uchar, longlong, ushort, uint, int64, uint64, size64_t, ssize64_t, _off64_t, uint64_t, ptrdiff_t])
 AC_TYPE_OFF_T