[tex-k] Total number of words in pltotf

[Hironobu Yamashita]

Follow-up:

> What is worse, 'uptftopl' fails to allocate memory for huge
> GLUEKERN table like this (gklarge0.pl),
> https://gist.github.com/aminophen/2839eb95e33d8c0d450c2ef8c8f8967d
> 
> $ uptftopl gklarge0 temp
> Input file is in YOKO-kumi kanji tfm format.
> uptftopl(17192,0x7fff760ef000) malloc: *** mach_vm_map(size=18446744073709428736) failed (error code=3)
> *** error: can't allocate region
> *** set a breakpoint in malloc_error_break to debug
> fatal: memory exhausted (realloc of 18446744073709426269 bytes).

The origin of the above error itself should be also resolved,
so I'll add a check of lf<2^{15} into ptftopl.ch.

Hironobu Yamashita