make(1): treat malformed :range, :ts and :[...] as errors

Before, integer overflow in the :[1..2] modifier had not been detected,
and the actual behavior varied between ILP64 and LP64I32 machines.

Before, the :ts modifier accepted character literals like \012345 and
\x1F600, which don't fit in a single character and were thus truncated.

Before, the :range modifier issued an "Unknown modifier" error message
for :range=x, which was not quite correct.  The error message in this
case is now "Invalid number".

(rillig)