[PATCH] Add override file support.

[James Hunt]

Add override file support.

* init/conf.c:
  - conf_reload_path(): Now takes an extra override_path parameter.
  - is_conf_file() / is_conf_file_std() / is_conf_file_override(): New
    functions to determine type of given file path.
  - toggle_conf_name(): New function which convert a conf file
    name to an override name and vice versa.
  - majority of remaining functions updated to handle override
    files.
* init/conf.h: Prototypes.
* init/job_class.c: Whitespace.
* init/man/init.5: Updated to document override file support.
* init/man/init.8: Added reference to control-alt-delete(7) man page.
* init/paths.h: New macros CONF_EXT_OVERRIDE, CONF_EXT_STD,
  IS_CONF_FILE_OVERRIDE and IS_CONF_FILE_STD.
* init/parse_conf.c: Added assertion to remind us forcibly to add
  override-handling code for directories if we ever allow content in
  'init.conf'.
* init/parse_job.c (parse_job): Additional parameter 'update' to
  allow override files to replace existing Job details.
* init/parse_job.h: Updated parse_job() prototype.
* init/test_conf.c
  - New macros TEST_ENSURE_CLEAN_ENV() and
    TEST_FORCE_WATCH_UPDATE().
  - test_override(): New function.
  - test_toggle_conf_name(): New function.
* init/test_parse_job.c:
  - Updated for extra parse_job() parameter.
  - added a test feature to test_parse_job() to exercise new
    parameter to parse_job().
* util/man/initctl.8: Clarified what it means to restart a job.

Code:

https://code.launchpad.net/~jamesodhunt/upstart/upstream-override-support

Merge Proposal:

https://code.launchpad.net/~jamesodhunt/upstart/upstream-override-support/+merge/63569

Regards,

James.