cache terminal size, add SIGWINCH handler to reset

Refactoring getcols, yet again. We do the following:

1) Introduce a static global in src/pacman/util.c
2) getcols always prefers this cached value, but will derive it from
the COLUMNS environment var, the characteristics of stdout, or a sane
default (in that order).
3) Introduce a SIGWINCH signal handler to reset the cached value,
meaning we only call ioctl when we don't know the value.

On my machine, pacman -Syy goes from ~4300 ioctl calls to 3.

0 files changed, 0 insertions, 0 deletions