[ccache] ccache version 3.4 has been released

[Joel Rosdahl]

ccache version 3.4 is now available.

Details may be read in the release notes:

    http://ccache.samba.org/releasenotes.html#_ccache_3_4

Source archives are available here:

    https://www.samba.org/ftp/ccache/ccache-3.4.tar.bz2
    https://www.samba.org/ftp/ccache/ccache-3.4.tar.gz
    https://www.samba.org/ftp/ccache/ccache-3.4.tar.xz

The source archives have been signed with my OpenPGP key (ID 5594ADB8,
fingerprint 5A93 9A71 A467 92CF 5786 6A51 996D DA07 5594 ADB8):

    https://www.samba.org/ftp/ccache/ccache-3.4.tar.bz2.asc
    https://www.samba.org/ftp/ccache/ccache-3.4.tar.gz.asc
    https://www.samba.org/ftp/ccache/ccache-3.4.tar.xz.asc

You can run "gpg --verify ccache-3.4.tar.*.asc" to check the source
archive integrity after download.

New features and enhancements:

- The compiler option form "--sysroot arg" is now handled like the
  documented "--sysroot=arg" form.

- Added support for caching ".su" files generated by GCC flag
  "-fstack-usage".

- ccache should now work with distcc's "pump" wrapper.

- The optional unifier is no longer disabled when the direct mode is
  enabled.

- Added support for nvcc compiler options "--compiler-bindir/-ccbin",
  "--output-directory/-odir" and "--libdevice-directory/-ldir".

- Boolean environment variable settings no longer accept the following
  (case-insensitive) values: "0", "false", "disable" and "no". All other
  values are accepted and taken to mean "true". This is to stop users
  from setting e.g. "CCACHE_DISABLE=0" and then expect the cache to be
  used.

- Improved support for "run_second_cpp = false": If combined with
  passing "-fdirectives-only" (GCC) or "frewrite-includes" (Clang) to
  the compiler, diagnostics warnings and similar will be correct.

- An implicit "-MQ" is now passed to the preprocessor only if the object
  file extension is non-standard. This should make it easier to use
  EDG-based compilers (e.g. GHS) which don't understand "-MQ".

- ccache now treats an unreadable configuration file just like a missing
  configuration file.

- Documented more pitfalls with enabling "hard_links"
  ("CCACHE_HARDLINK").

- Documented caveats related to colored warnings from compilers.

Bug fixes:

- File size and number counters are now updated correctly when files are
  overwritten in the cache, e.g. when using "CCACHE_RECACHE".

- "run_second_cpp" is now forced for nvcc.

- Fixed how the nvcc options "-optf" and "-odir" are handled.

-- Joel