Fix up libthread to actually do threading on windows.
Merge pull request #149 from larskanis/master

Support blocking function calls for Ruby 1.8 on win32
Add documentation to FFI::AbstractMemory.
Do not assume that -m32/-m64 are always available
Test for other macros that identify a GNU userland
A more portable GNU make detection

If there is a `gmake` in the path, then that's GNU make. Otherwise, it
is just `make`.
Generalize Linux support for all GNU systems
Merge pull request #146 from tekwiz/libtest2

Libtest Threading Fix
Merge pull request #154 from terceiro/portability

GNU (non i386/amd64 linux) portability patches
Merge pull request #153 from sdaubert/master

Add documentation to FFI::AbstractMemory
Fixup threadVrV() signature for posix
Documentation for FFI::Pointer, FFI::Type, FFI::Type::Builtin,
  FFI::Type::Mapped, FFI::NativeType, FFI::StrPtrConverter.
Minor correction for FFI::AbstractMemory#put_bytes (old doc seems to
  be for #get_bytes).
Merge pull request #155 from sdaubert/master

Documentation for Pointer, Type, Type::Builtin, Type::Mapped, NativeType, StrPtrConverter
Add documentation for DataConverter, LastError, AutoPointer, FFI::IO, Library, Platform and FFI class methods from types.rb.
Merge pull request #156 from sdaubert/master

Add more documentation
Add documentation for ArrayType, Buffer, DynamicLibrary, Function, Enum, Enums
and ConstGenerator.
Merge pull request #158 from sdaubert/master

More documentation
The platform/OS-arch directories for linux are called linux, not gnu.
Improved cleanup of platform.rb
Complete fix for platform detection

Test for GNU systems by checking whether the GNU libc is available.
Also added a spec that reproduces #137.