#10 add headers for statvfs

Author: Vincent Landgraf

ext/vmstat/extconf.rb

@@ -33,7 +33,7 @@
 if have_func 'statfs'
   have_struct_member('struct statfs', 'f_type', ['sys/param.h', 'sys/mount.h', 'sys/statfs.h'])
   have_struct_member('struct statfs', 'f_fstypename', ['sys/param.h', 'sys/mount.h'])
-elsif have_func 'statvfs'
+elsif have_func 'statvfs', ['sys/types.h', 'sys/statvfs.h']
   have_struct_member('struct statvfs', 'f_basetype', ['sys/types.h', 'sys/statvfs.h'])
 end