Win32: additional error code NGX_EEXIST_FILE (ticket #910). On Windows there are two possible error codes which correspond to the EEXIST error code: ERROR_FILE_EXISTS used by CreateFile(CREATE_NEW), and ERROR_ALREADY_EXISTS used by CreateDirectory(). MoveFile() seems to use both: ERROR_ALREADY_EXISTS when moving within one filesystem, and ERROR_FILE_EXISTS when copying a file to a different drive.

--- a/src/os/unix/ngx_errno.h
+++ b/src/os/unix/ngx_errno.h
@@ -25,6 +25,7 @@ typedef int               ngx_err_t;
 #define NGX_EACCES        EACCES
 #define NGX_EBUSY         EBUSY
 #define NGX_EEXIST        EEXIST
+#define NGX_EEXIST_FILE   EEXIST
 #define NGX_EXDEV         EXDEV
 #define NGX_ENOTDIR       ENOTDIR
 #define NGX_EISDIR        EISDIR