mksh R59

R59 has some major fixes, also introducing breaking changes:

• Repair out-of-tree builds
• Work around a glibc on Hurd issue in testsuite
• OS/2 filesystem mtime granularity is two seconds (as in FAT)
• Replace while with goto: Coverity was confused
• Fix invocation of some builtins when external utility absent
• Improve automatic executable suffix for test builtin
• Style code, refactor, clean up, optimise
• Use cached egid in test builtin
• Make bind builtin output reentry-safe; safety fixes
• If basename(argv[0]) after leading dash removal begins with an r enable restricted shell flag
• Fix code example in manpage for how tab completion escapes
• Match full extglob pattern RHS of [[ string comparison like ksh93
• Implement which with -a in dot.mkshrc
• Remove global builtin (use typeset -g)
• alias, command, whence: Print alias names quoted
• Implement a new quote-region (Esc+Q) editing command
• Document all built-in aliases and those aliases and functions shipped in dot.mkshrc; completely overhaul builtin and reserved word documentation, for consistency
• The manual page now features properly spaced em dashes
• Document that test x = y doesn’t extglob, only [[ x = y ]] does