changes in sbcl-1.5.7 relative to sbcl-1.5.6:
* platform support:
** many bug fixes to the experimental 64-bit PowerPC/Linux port, to the
extent that the little-endian variant passes all applicable tests in
the regression test suite; the big-endian variant currently has some
failures
** experimental support for sb-threads on 64-bit PowerPC/Linux
** support threads on x86-64 Sun OS (lp#1841280)
** handle PAX restrictions on mprotect() on NetBSD
** experimental support for HaikuOS
** the runtime is built as a position-independent executable by default on
x86-64 Linux and x86-64 Darwin
* fixes and enhancements related to Unicode:
** update of the data files to Unicode 8.0
** fix a bug in the implementation of the Unicode line breaking algorithm
regarding hebrew letters and hyphens
* enhancement: add a restart to OPEN with :IF-EXISTS :ERROR to allow
re-opening with :APPEND. (lp#806398, reported by Tobias Rittweiler)
* bug fix: compiler optimizations on SEARCH with :FROM-END T didn't account
for the empty sequence. (lp#1844821)
* bug fix: handle SETF of nested empty VALUES correctly. (lp#1806478)
* optimization: FLOOR and CEILING on rationals are simpler, and the
compiler's understanding of them is better.