added a check for unistd.h which is needed for STDERR_FILENO.

src/mpe2/src/logging/configure.in

@@ -201,7 +201,7 @@ else
     AC_C_BIGENDIAN
 fi
 
-AC_CHECK_HEADERS(stdio.h stdlib.h string.h sys/time.h sys/types.h sys/bitypes.h)
+AC_CHECK_HEADERS(stdio.h stdlib.h string.h unistd.h sys/time.h sys/types.h sys/bitypes.h)
 
 
 dnl