Procps library previously held functions that were about either
listing or finding signal names. These are not really the right
location for a library about reading procfs.
This patch handles signal related functions in two ways:
For functions purely found in skill, these have been moved back
into this binary as they are used nowhere else.
For functions used across the binaries, these have been moved
into include/signals.h and lib/signals.c. Besides formatting,
these functions are largely the same.
To assist the skill functions, two functions to access the
signal map array have been added to lib/signals.c
