Blender Git Loki

Fix for debug-only crash when setting "Any" keymap input type

Another one of those assert crashes when passing values != than 1 and 0
(in this case the value is -1)

Notes from reviewer:
--------------------
These should really be enums. since valid values are KM_ANY,
KM_MOD_FIRST, KM_MOD_SECOND.

But can see at some point this was changed from an enum so... I guess
this is the only way.

Reviewers: campbellbarton

Differential Revision: https://developer.blender.org/D1227