Fix tests.
Merge topic 'clang-features' into next

2d19e956 Fix tests.
Add the WriteCompilerDetectionHeader module.

Provide a function to write a portable header to detect compiler
features.
Features: Record for Clang 3.4
Merge topic 'clang-features' into next

72c18e79 Features: Record for Clang 3.4
c7d4f110 Add the WriteCompilerDetectionHeader module.