Fix NEWS.txt syntax to please AsciiDoc

Yet another thing AsciiDoc isn't good at.
Merge branch 'maint'

* maint:
  Fix NEWS.txt syntax to please AsciiDoc
Refactor conf code into bool_to_string function
Add "read-only direct" setting
Do not rely on pids being unique

Based on a patch by Mike Frysinger <vapier@gentoo.org>:

"Linux supports creating pid namespaces cheaply and running processes
inside of them. When you try to share a single cache among multiple such
runs, the fact that the code relies on pid numbers as globally unique
values quickly fails. Instead, switch to standard mkstemp to generate temp
files for us."
Don't try to reset a non-existing stats file

This avoids "No such file or directory" messages in the ccache log when the
cache directory doesn't exist.
Merge maint into master (using imerge)
Improve temporary file creation functions and usage
Improve execute() to take FDs instead of filenames

This means that execute() no longer needs to recreate the temporary
stdout/stderr files needlessly.

Note: ccache will no longer build on win32 after this change, but I don't
know what needs to be done to win32execute(). I leave that to those who
know.
test: Fix "profile-use" failure on GCC 4.9