Features: Escape the COMPILE_OPTIONS for dialects.

Allow for future handling as a list, not a string which may contain
whitespace.
WCDH: Remove noise from generated defines.

The DECL part is redundant, and the language part is not needed. The
source language and context already determines the language, so there
is no need to repeat it in the define name.
Project: Detect other compilers before detecting Clang.

Commit v2.8.10.1~5^2 (Fix PathScale compiler id for Clang-based
upstream, 2012-11-05) re-ordered the detection logic for PathScale.

Other compiler vendors are also producing Clang-based frontends, so
detect "actual" Clang as one of the last compilers to allow for others
doing the same.

    http://llvm.org/devmtg/2014-04/PDFs/Posters/ClangIntel.pdf
    http://docwiki.embarcadero.com/RADStudio/XE5/en/Clang-based_C%2B%2B_Compilers
WCDH: Fix compiler id test for compatibility macros.

Enable the alignment features for Clang.
Merge topic 'features-cleanups' into next

631f0c6e WCDH: Fix compiler id test for compatibility macros.
52cc7306 Project: Detect other compilers before detecting Clang.
6699d2b0 WCDH: Remove noise from generated defines.
f8c6b43b Features: Escape the COMPILE_OPTIONS for dialects.