mksh R52b

R52b is a strongly recommended bugfix-only release:

• Recognise ksh93 compiled scripts and LZIP compressed files as binary (i.e. to not run as mksh plaintext script)
• Document that we will implement locale tracking later
• Add EEXIST to failback strerror(3)
• Make set -C; :>foo race-free
• Don’t use unset in portable build script
• Plug warning on GNU/kFreeBSD, GNU/Hurd
• Document read -a resets the integer base
• Fix manpage: time is not a builtin but a reserved word
• Make exit (and return) eat -1
• parse “$( (( … ) … ) … )” correctly (LP#1532621), Jan Palus
• reduce memory footprint by free(3)ing more aggressively
• fix buffer overrun (LP#1533394), bugreport by izabera
• correctly handle nested ADELIM parsing (LP#1453827), Teckids
• permit “read -A/-a arr[idx]” as long as only one element is read; fix corruption of array indicēs with this construct (LP#1533396), izabera
• Sanitise OS-provided signal number in even more places
• As requested by Jörg, be clear manpage advice is for mksh
• Revert (as it was a regression) POSIX bugfix from R52/2005 related to accent gravis-style command substitution until POSIX decides either way
• Handle export et al. after command (Austin#351)
• Catch EPIPE in built-in cat and return as SIGPIPE (LP#1532621)
• Fix errno in print/echo builtin; optimise that and unbksl
• Update documentation, point out POSIX violation (Austin#1015)