Make the 0.5 version the default, so that code wanting the actual
implemented version can get a proper versioned depdendency. For code
linked against the old version, make it available as an alias.
Use local getprogname()/setprogname() instead of reimplementing them
locally. Use clearenv() if available, not just on glibc. Use bool
instead of _Bool. Use paranthesis on sizeof. Fold the SPT_MIN macro
into spt_min(). Make spt_init() static. Avoid unnecessary gotos.
This centralizes the setting so there's no duplication anymore,
makes sure the user supplied variables are never overridden, and
are only set when using gcc.
Reported-by: Samuli Suominen <ssuominen@gentoo.org>
