Fix spurious gcc warning in cc_file.c

gcc 4.6.3 (present in Ubuntu 12.04) is smart enough to look at
get_size and see that it does not always assign to *size_out, but not
smart enough to figure out that it always assigns to *size_out when it
returns 0.  As a result, it outputs two warnings which we treat as
errors.  Add an initial assignment to *size_out at the beginning of
get_size to work around this.

ticket: 8026
Fix input race condition in t_skew.py

In two of the kinit tests run by t_skew.py, we expect kinit to exit
before reading the password.  If we supply a password input for those
commands, we can fail with a broken pipe exception if the master
process tries to write the password after the slave process exits.

Also correctly check the output of the last kinit invocation.

ticket: 8034 (new)
target_version: 1.13.1
tags: pullup
Fix minor cleanup issue in file ccache

If we fail to open the cache file in fcc_initialize, we could wind up
calling close(-1) which is harmless but incorrect.  Avoid this by
initializing fd and conditionalizing its cleanup.

ticket: 8026
Remove des3 and arcfour from supported_enctypes

The des3 and arcfour (rc4) enctypes use weak string-to-key algorithms,
and should not be used for producing password-derived keys.

ticket: 7903
Update example enctypes in kdc_conf.rst

Use modern enctypes for values of master_key_type and
supported_enctypes in the example kdc.conf in kdc_conf.rst.

ticket: 8035 (new)
target_version: 1.13.1
tags: pullup
Add custom error formatting (err_fmt config param)

    Add [libdefaults] err_fmt, a parameter for additional formatting of
    error messages.  %C gets substituted with the numeric error code.
    %M gets substituted with the original error message.

    For example:

        [libdefaults]
                err_fmt = %M (http://docs.foo.example/krb5/errors/%C)

    will produce errors like:

        Cannot find KDC for realm "FOO.EXAMPLE" (http://docs.foo.example/krb5/errors/-1765328230)
Include file ccache name in error messages

Conflicts:
	src/lib/krb5/ccache/cc_file.c