added a check for the xlc compiler on AIX, and if that is detect we use

  AC_CHECK_FUNCS( gmtime_r )

  AC_DEFINE(_THREAD_SAFE, 1, [define this if you need it to compile thread-safe code])

  dnl check if this is the IMB xlc compiler

  dnl Details thanks to => http://predef.sourceforge.net/

  AC_MSG_CHECKING([if this is the xlc compiler])

  AC_EGREP_CPP([^__xlC__], [__xlC__],

         dnl action if the text is found, this it has not been replaced by the

         dnl cpp

         XLC="no"

         AC_MSG_RESULT([no]),

         dnl the text was not found, it was replaced by the cpp

         XLC="yes"

         AC_MSG_RESULT([yes])

         CFLAGS="$CFLAGS -qthreaded"

       )

fi