Allow one to force lower_case_table_names to 0, even if the file system is case insensitive. This fixes some issues on Mac OS X (Bug #2994)
Added variables "lower_case_file_system", "version_compile_os" and "license"


mysql-test/t/lowercase_table3-master.opt:
  Rename: mysql-test/t/lowercase_table2-master.opt -> mysql-test/t/lowercase_table3-master.opt
mysys/my_getopt.c:
  Ensure that one can't from the command line set a variable too small (could happen when sub_size was set)
sql/mysql_priv.h:
  Added lower_case_file_system
sql/mysqld.cc:
  Allow one to force lower_case_table_names to 0, even if the file system is case insensitive
sql/set_var.cc:
  Added variable "lower_case_file_system"
  Added variable "version_compile_os"
  Added variable "license"
sql/set_var.h:
  Added support for read only strings
sql/sql_select.cc:
  Make join optimizer killable