KEY_LDSCRIPT replaces the bare literal at both the table entry and the
lookup, so a typo cannot silently fall back to the layout-moving
default; the regeneration recipe notes that overrides must survive a
refresh; a board pinning an override on an Arduino core <= 2.4.2 warns
that the layout cannot be honored; and board_ld_script gains the test
pinning d1_wroom_02's shipped layout and the size defaults.
J. Nick Koston