it BROKEN if clang is detected. In order to do that handle do-build target since
the distribution Makefile includes <bsd.prog.mk> which does not handle
USE_GCC=any well.
Setting WRKSRC to WRKDIR would also not work as the subr script would
overwrite a binary file with the same name. Cleanup, repack and self host this
abomination of a flat distfile in order to avoid ugly extract hacks. While
here also mark MAKE_JOBS_SAFE.
For a while now bsdtar is able to autotermine compression and archive format.
Let's then use tar directly instead of piping to tar.
Now USE_BZIP2 and USE_XZ only set EXTRACT_SUFX to the right format
literal name_enable wherever possible, and ${name}_enable
when it's not, to prepare for the demise of set_rcvar().
In cases where I had to hand-edit unusual instances also
modify formatting slightly to be more uniform (and in
some cases, correct). This includes adding some $FreeBSD$
tags, and most importantly moving rcvar= to right after
name= so it's clear that one is derived from the other.
