Fix the stderr output catcher.
Merge topic 'target_compiler_features' into next

5b5944a Fix the stderr output catcher.
Record the compilers capable of the cxx_delegating_constructors feature.
Add target_compiler_features command.
Make COMPILER_FEATURES available as a target property.
Allow populating compiler_features using generator expressions.
Transitively evaluate compiler features.

Extend the interface of the target_compiler_features command with
PUBLIC and INTERFACE keywords. Populate the INTERFACE_COMPILER_FEATURES
target property if they are set. Consume the INTERFACE_COMPILER_FEATURES
target property from linked dependent targets to determine the final
required compiler features and the compile flag, if needed.
Add the WriteCompilerDetectionHeader module.

Provide a function to write a portable header to detect compiler
features.
Add a variable for the compiler command to compile a source file.

Use the variable in CxxFeatureTesting.cmake.
Merge topic 'target_compiler_features' into next

22c1d2f Add a variable for the compiler command to compile a source file.
179e368 Add the WriteCompilerDetectionHeader module.
5268d6f Transitively evaluate compiler features.
5594aa6 Allow populating compiler_features using generator expressions.
0e27f31 Make COMPILER_FEATURES available as a target property.
35cab24 Add target_compiler_features command.
bf27080 Record the compilers capable of the cxx_delegating_constructors feature.