Define _XOPEN_SOURCE=500 in posix mode - utmp - simple login manager  
  HTML git clone git://git.suckless.org/utmp
   DIR Log
   DIR Files
   DIR Refs
   DIR README
   DIR LICENSE
       ---
   DIR commit 81d0a50c7392fc4c985b0e71e708ccdd3815441a
   DIR parent 3900c06929f0184d80c0be3145afbb807b910471
  HTML Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
       Date:   Sun, 22 Feb 2015 16:28:42 +0000
       
       Define _XOPEN_SOURCE=500 in posix mode
       
       utmpx interface is well defined only when _XOPEN_SOURCE=500
       
       Diffstat:
         M config.posix                        |       2 +-
       
       1 file changed, 1 insertion(+), 1 deletion(-)
       ---
   DIR diff --git a/config.posix b/config.posix
       @@ -7,7 +7,7 @@ PREFIX = /usr/local
        MANPREFIX = ${PREFIX}/share/man
        
        # flags
       -CPPFLAGS += -DVERSION=\"${VERSION}\"
       +CPPFLAGS += -D_XOPEN_SOURCE=500 -DVERSION=\"${VERSION}\"
        
        # Objects