* Migrate some tmk_core files to quantum

* Fix build errors

* Add target 'build-for-compare' to `build_keyboard.mk`

The `build-for-compare` target provides an easy way to check the md5 checksum of the generated binary.

You can easily see if there is any change in the generated binaries between the two versions, as in the example below.

```
$ git checkout 0.11.0
M	build_keyboard.mk
M	tmk_core/rules.mk
Note: checking out '0.11.0'.
HEAD is now at c66df1664 2020 November 28 Breaking Changes Update (#11053)

$ make helix:all:build-for-compare | grep ^MD5
MD5 (.build/helix_rev2_default.hex) = 5c3606562c944bb4d18832e601b45d4a
MD5 (.build/helix_rev2_edvorakjp.hex) = 9e43d13d389d518ba7e99cd7337e28d6
MD5 (.build/helix_rev2_five_rows.hex) = 8bcb61c2fd5d237c2997f2fa007d4934
MD5 (.build/helix_rev2_five_rows_jis.hex) = b97cd818d52f73ca2d4e78c86d90a791
MD5 (.build/helix_rev2_froggy.hex) = c492172364188f4e2918b10bf0f3a0a6
MD5 (.build/helix_rev2_froggy_106.hex) = b0861fd735a8f81881a8c02730641a2b
MD5 (.build/helix_rev2_led_test.hex) = 5c97d982a5da5cfb3dacb28a8934b81d
MD5 (.build/helix_rev2_xulkal.hex) = 01f603dc46bcf9094d7e106831d8f5b1
MD5 (.build/helix_rev2_yshrsmz.hex) = 5a008bca2d0c5790a151c02834c529ba

$ git checkout 0.11.1
M	build_keyboard.mk
M	tmk_core/rules.mk
Previous HEAD position was c66df1664 2020 November 28 Breaking Changes Update (#11053)
HEAD is now at cc08e3082 nix-shell: add milc dependency (#11086)

$ make helix:all:build-for-compare | grep ^MD5
MD5 (.build/helix_rev2_default.hex) = 5c3606562c944bb4d18832e601b45d4a
MD5 (.build/helix_rev2_edvorakjp.hex) = 9e43d13d389d518ba7e99cd7337e28d6
MD5 (.build/helix_rev2_five_rows.hex) = 8bcb61c2fd5d237c2997f2fa007d4934
MD5 (.build/helix_rev2_five_rows_jis.hex) = b97cd818d52f73ca2d4e78c86d90a791
MD5 (.build/helix_rev2_froggy.hex) = c492172364188f4e2918b10bf0f3a0a6
MD5 (.build/helix_rev2_froggy_106.hex) = b0861fd735a8f81881a8c02730641a2b
MD5 (.build/helix_rev2_led_test.hex) = 5c97d982a5da5cfb3dacb28a8934b81d
MD5 (.build/helix_rev2_xulkal.hex) = d848383adfd7463b138c6da179cf1436
MD5 (.build/helix_rev2_yshrsmz.hex) = 5a008bca2d0c5790a151c02834c529ba
```

* make builds reproducable by default

* update build_keyboard.mk: remove 'build-for-compare' target

* GNU make (3.81) on macOS 10.14(Mojave) does not have the 'undefine' directive.

* Adopted fauxpark's suggestion.

* Update tmk_core/rules.mk

Co-authored-by: Ryan <fauxpark@gmail.com>

* update tmk_core/rules.mk

* fix tmk_core/rules.mk

Co-authored-by: Zach White <skullydazed@gmail.com>
Co-authored-by: Ryan <fauxpark@gmail.com>

* Better handle LTO_ENABLE

Especially when calling from command line

* Replace LINK_TIME_OPTIMIZATION_ENABLE with LTO_ENABLE

* Remove long for LTO from show_options.mk

* Branch point for 2020 May 30 Breaking Change

* Migrate `ACTION_LAYER_TOGGLE` to `TG()` (#8954)

* Migrate `ACTION_MODS_ONESHOT` to `OSM()` (#8957)

* Migrate `ACTION_DEFAULT_LAYER_SET` to `DF()` (#8958)

* Migrate `ACTION_LAYER_MODS` to `LM()` (#8959)

* Migrate `ACTION_MODS_TAP_KEY` to `MT()` (#8968)

* Convert V-USB usbdrv to a submodule (#8321)

* Unify Tap Hold functions and documentation (#8348)

* Changing board names to prevent confusion (#8412)

* Move the Keyboardio Model01 to a keyboardio/ subdir (#8499)

* Move spaceman keyboards (#8830)

* Migrate miscellaneous `fn_actions` entries (#8977)

* Migrate `ACTION_MODS_KEY` to chained mod keycodes (#8979)

* Organizing my keyboards (plaid, tartan, ergoinu) (#8537)

* Refactor Lily58 to use split_common (#6260)

* Refactor zinc to use split_common (#7114)

* Add a message if bin/qmk doesn't work (#9000)

* Fix conflicting types for 'tfp_printf' (#8269)

* Fixed RGB_DISABLE_AFTER_TIMEOUT to be seconds based & small internals cleanup (#6480)

* Refactor and updates to TKC1800 code (#8472)

* Switch to qmk forks for everything (#9019)

* audio refactor: replace deprecated PLAY_NOTE_ARRAY (#8484)

* Audio enable corrections (2/3) (#8903)

* Split HHKB to ANSI and JP layouts and Add VIA support for each (#8582)

* Audio enable corrections (Part 4) (#8974)

* Fix typo from PR7114 (#9171)

* Augment future branch Changelogs (#8978)

* Revert "Branch point for 2020 May 30 Breaking Change"

* add missing shutdown_user()

* use reset_keyboard() from quantum