extras/keymap: fix hash table collisions

extras/keymap: fix hash table collisions

More than one key name was mapped to the same key, due to linux/input.h
defining some aliases (in particular, KEY_HANGUEL, KEY_SCREENLOCK,
KEY_MIN_INTERESTING). These caused hash table collisions.

Changed the generation of the tables to ignore these aliases, and updated all
keymaps to use the canonical name.

This was detected by llvm-clang-analyzer. Thanks to Lennart Poettering for
doing these checks and pointing this out!

https://launchpad.net/bugs/426647