HAVE_TIMEZONE and cygwin

[Billinghurst, David (CRTS)]

The cygwin patch for natSystem.cc
(http://gcc.gnu.org/ml/java-patches/2002-q2/msg00252.html) 
probably should read something like

#elif HAVE_UNDERSCORE_TIMEZONE
   tzoffset = _timezone;
#elif HAVE_TIMEZONE
   // timezone is secs WEST of UTC.
   tzoffset = timezone;	
#else
   // FIXME: there must be another global if neither
tm_gmtoff nor timezone
   // is available, esp. if tzname is valid.


To do this we need to add to libjava/configure.in 
a test something like

   AC_TRY_COMPILE([#include <time.h>], [long z2 = _timezone;],
     [AC_DEFINE(HAVE_UNDERSCORE_TIMEZONE)
      AC_MSG_RESULT(yes)],
     [AC_MSG_RESULT(no)])])

and preferably get the existing test    

   AC_TRY_COMPILE([#include <time.h>], [long z2 = timezone;],
     [AC_DEFINE(HAVE_TIMEZONE)
      AC_MSG_RESULT(yes)],
     [AC_MSG_RESULT(no)])])

to fail for the cygwin <time.h> which has
  char *_EXFUN(timezone, (void));