Fix compile error with C99 whilc buidling openssh

define and inline conflict with C99.

The patch is based on the cygwin source.
https://cygwin.com/viewvc/src/winsup/cygwin/include/asm/byteorder.h?revision=1.15&view=markup
https://cygwin.com/viewvc/src/newlib/libc/include/_ansi.h?revision=1.10.2.1&view=markup