Bug #49984  	Test 'rpl_loaddata_symlink' fails with "Could not find target log"

Sometimes the symbolic link is available on Windows if
you have some Unix (emulation) layer installed like
Cygwin, MKS or other. But symbolic link is not always
available. It depends on versions, file volume and
system environment of Windows. And the symbolic link
is not typically used on Windows, at least not in the
degree and style they are used on Unix. We can not 
change the test case to do without symbolic link,
because the test case is used to test that if the
symbolic link works fine.

To fix the problem, skip the test on windows.


mysql-test/suite/rpl/t/rpl_loaddata_symlink.test:
  Added code to skip the test on windows.