REVIEW-3210: Removed 'duplicate' gcc 4.x versions from testing
Include correct GCC assembler arguments for target platform

- Tests for assembler are now targeted at 32bit intel on all os's
Split up the native binaries language plugins so it's possible to choose the tool chain support you require.
Explicitly configure toolChain used in integration test, rather than just relying on path/environment.

- SingleToolChainTestRunner no longer configures the runtime environment for a tool chain: it just selects the tool chain to run with
    - AbstractInstalledToolChainSpec add build script configuration for selected tool chain
- New ToolChainDiscoveryIntegrationTest tests that an unconfigured tool chain will run off the runtime environment
- Exposes breakages in several Clang tool chain tests
ClangToolChain now correctly targets platform architecture

- Extracted GnuCompatiblePlatformToolChain from GccToolChain
- Updated BinaryPlatformIntegrationTest to run on all platforms
Removed obsoleted test (that now fails)
ExecutableFixture uses toolChain runtime environment for execution

- Mingw and cygwin executables can then be tested without using 'install'
Codenarc fix