Problem:
if a user was granted privileges on database "d1",
it also was able to act on "D1" (i.e. in upper case),
even on Unix with case sensitive file system.

Fix:
Initialize grant hash to use binary comparison
if lower_case_file_system is not set (on most unixes),
and case insensitive comparison otherwise (Windows, MacOSX).


sql/sql_acl.cc:
  Initialize hash to use binary comparison with case sensitive FS.
mysql-test/include/have_case_sensitive_file_system.inc:
  New BitKeeper file ``mysql-test/include/have_case_sensitive_file_system.inc''
  Backporting from 5.1
mysql-test/r/case_sensitive_file_system.require:
  New BitKeeper file ``mysql-test/r/case_sensitive_file_system.require''
  Backporting from 5.1
mysql-test/r/lowercase_fs_off.result:
  Adding test case
mysql-test/t/lowercase_fs_off.test:
  Adding test case