Add Travis CI config
Add clang-format configuration
Revert the C++ compatibility changes.

- These only make it harder to track the official Apple version at opensource.apple.com.
- Visual Studio 2013 supports C99 now
- For dispatch i/o, we could get GCC compatibility by compiling this file only as C++, and substituting C++11 lambdas for blocks with some preprocessor shenanigans
Rename some constants for cross-platform compat
Rename #define to match Mavericks source tree
Travis: Explicitly specify C/C++ compilers

The test 'dispatch_cpp' was failing to compile, as the system compiler
(GCC) was being picked up instead of Clang.
Add support for eventfd even if glibc doesn't expose it

RHEL 5.10 appears to support eventfd, just not via glibc. We syscall()
it instead.
Squash warnings about unused variables
Simplify build system

- Remove automake build system -- I don't have the knowledge to maintain
  it.
- Remove Darwin-specific stuff from CMake build system -- this was
  pretty superfluous, and never tested.
- Make compatible with CMake 2.8.7 for ancient distros (and Travis CI).
- Combine the various CMake helper functions into a single file
- Begin work on removing dependency on libBlocksRuntime.
Fix incompatibility between Clang and some variants of unistd.h

The presence of '__block' as a parameter name in unistd.h in some Glibc
releases caused Clang to issue a compiler error.