Fix compilation issues in the updated build system

[lpetre-ulb]

(Supersedes #137)

Description

Fixes all compilation issues in the updated build system up to the point where all RPM packages can be built seamlessly on gem904daq04. Further runtime tests are going to be performed in order to check the functionalities.

The changes are the following:

• Update the config submodule in order to get the new PETA_PATH environment variable;
• Cherry-pick the commits from Add log4cplus version awareness, fix #116 #117;
• Compile against C++14 for the return type deduction support;
• Fix a warning message in order to prevent memory corruption.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Motivation and Context

Compile the templated RPC framework with the updated build system.

How Has This Been Tested?

All RPM packages can be built out-of-the box on gem904daq04.

[jsturdy]

Can we agree that we don't merge PRs on the weekend, unless they are specific hotfixes needed to be addressed for operational reasons?

[lpetre-ulb]

Well, if the merging criteria are met, I don't see any good argument against merging PR on the weekend. If people want to work on the weekend, that's their problem. ;) If the merging criteria are too relaxed, they can be tighten (ideally with a CI which checks that all tests still pass).