Fix for #include <errno.h> on systems without this header.
Fix for #include <errno.h> on systems without this header.

issue #161


git-svn-id: 1b2893900746d3474b20c0dea7456040123c3b26@575 21eae674-98b7-11dd-bd71-f92a316d2d60

jpoirier/picoc