Include errno.h in zipint.h.

Define missing error codes centrally in zipint.h.
Remove errno.h inclusion everywhere else.
diff --git a/lib/zip_source_filep.c b/lib/zip_source_filep.c
index 5ad4285..191a81c 100644
--- a/lib/zip_source_filep.c
+++ b/lib/zip_source_filep.c
@@ -31,15 +31,13 @@
   IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-
-#include "zipint.h"
-
 #include <sys/stat.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include "zipint.h"
+
 #ifdef _WIN32
 /* WIN32 needs <fcntl.h> for _O_BINARY */
 #include <fcntl.h>
@@ -62,13 +60,6 @@
 typedef int mode_t;
 #endif
 
-/* at least MinGW does not provide this error code, see
- * http://sourceforge.net/p/mingw/bugs/242/
- */
-#ifndef EOVERFLOW
-#define EOVERFLOW EFBIG
-#endif
-
 struct read_file {
     zip_error_t error;      /* last error information */
     zip_int64_t supports;