Log Message:
Changes 3.2:
New features and improvements
- Added support for configuring ccache via one or several configuration files
  instead of via environment variables. Environment variables still have
  priority but are no longer the recommended way of customizing ccache
  behavior. See the manual for more information.
- Added support for compiler error/warning messages with color.
- Made creation of temporary directories and cache directories smarter to avoid
  unnecessary `stat` calls.
- Improved efficiency of the algorithm that scans for `__DATE_` and `__TIME__`
  tokens in the hashed source code.
- Added support for several binaries (separated by space) in `CCACHE_PREFIX`.
- The `-c` option is no longer passed to the preprocessor. This fixes problems
  with clang and Solaris's C++ compiler.
- ccache no longer passes preprocessor options like `-D` and `-I` to the
  compiler when compiling preprocessed output. This fixes warnings emitted by
  clang.
- Compiler options `-fprofile-generate`, `-fprofile-arcs`, `-fprofile-use` and
  `-fbranch-probabilities` are now handled without bailing.
- Added support for clang's `--serialize-diagnostic` option, storing the
  diagnostic file (`.dia`) in the cache.
- Added support for precompiled headers when using clang.
- Added support for clang `.pth` (pretokenized header) files.
- Changed the `-x` language option to use the new objective C standard for GCC
  and clang.
- On a cache miss, ccache now instructs the compiler to create the object file
  at the real destination and then copies the file into the cache instead of
  the other way around. This is needed to support compiler options like
  `-fprofile-arcs` and `--serialize-diagnostics`.
- ccache now checks that included files' ctimes aren't too new. This check can
  be turned off by adding `include_file_ctime` to the ``ccache sloppiness''
  setting.
- Added possibility to get cache hits based on filename, size, mtime and ctime
  only. On other words, source code files are not even read, only stat-ed. This
  operation mode is opt-in by adding `file_stat_matches` to the ``ccache
  sloppiness'' setting.
- The filename part of options like `-Wp,-MDfilename` is no longer included in
  the hash since the filename doesn't have any bearing on the result.
- Added a ``read-only direct'' configuration setting, which is like the
  ordinary read-only setting except that ccache will only try to retrieve
  results from the cache using the direct mode, not the preprocessor mode.
- The display and interpretation of cache size has been changed to use SI
  units.
- Default cache size is now 5 GB (was previously 1 GiB).
- Added configuration option to set the compression level of compressed object
  files in the cache.
- Added support for `@file` and `-@file` arguments (reading options from a
  file).
- `-Wl,` options are no longer included in the hash since they don't affect
  compilation.
- Bail out on too hard compiler option `-Wp,-P`.
- Optimized MD4 calculation code on little-endian systems.
- Various improvements and fixes on win32.
- Improved logging to the ccache log file.
- Added `--dump-manifest` command-line option for debugging purposes.
- Added `--with-bundled-zlib` configure option.
- Upgraded bundled zlib to version 1.2.8.
- Improved `dev.mk` to be more platform independent.
- Made the test suite work with clang and gcc-llvm on OS X.
- Various other improvements of the test suite.

Bug fixes
- Any previous `.stderr` is now removed from the cache when recaching.
- Fixed an issue when handling the `-arch` compiler option with an argument.
- Fixed race condition when creating the initial cache directory.
- Fixed test suite failures when `CC` is a ccache-wrapped compiler.