Cygwin: uname: Raise size of utsname fields and revamp uname(2) output

New format:

  sysname:      CYGWIN_NT-${osversion}-${os_build_number}[-WOW64]
  nodename:     `gethostname`
  release:      ${cygwin_version}-${API minor}.${arch}[.snap]
  version:      YYYY-MM-DD HH:MM UTC
  machine:      ${arch}
_GNU_SOURCE:
  domainname:   `getdomainname`
!_GNU_SOURCE:
  __domainname: `getdomainname`

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/common.din

@@ -1522,6 +1522,7 @@ ualarm SIGFE
 umask NOSIGFE
 umount SIGFE
 uname SIGFE
+uname_x SIGFE
 ungetc SIGFE
 ungetwc SIGFE
 unlink SIGFE