This removes the security features added by $SAFE = 1, and warns for access
or modification of $SAFE from Ruby-level, as well as warning when calling
all public C functions related to $SAFE.
This modifies some internal functions that took a safe level argument
to no longer take the argument.
rb_require_safe now warns, rb_require_string has been added as a
version that takes a VALUE and does not warn.
One public C function that still takes a safe level argument and that
this doesn't warn for is rb_eval_cmd. We may want to consider
adding an alternative method that does not take a safe level argument,
and warn for rb_eval_cmd.
by using ObjectSpace.trace_object_allocations.
`make test-all LEAK_CHECKER_TRACE_OBJECT_ALLOCATION=true` will print not
only leaked fds but also where it was created.
There are random failures:
> lib/rubygems/core_ext/kernel_require.rb:61:in `require':
> wrong number of arguments (given 1, expected 0) (ArgumentError)
http://ci.rvm.jp/results/trunk-jemalloc@silicon-docker/2275159
To check this failure, I added a small check code.
