Be nice to older (less clever) compiler versions

[ellert]

error: parameter declared 'auto'

[simonmichal]

Hi @ellert, thanks for the PR. The generic lambdas are part of C++14 standard, which is now officially required for XRootD. What is the platform / use case your are training to satisfy with those changes?

[ellert]

What is the platform / use case your are training to satisfy with those changes?

Until now building with -std=gnu++1y using the default compiler in RHEL/CentOS 7 worked.
The C++14 support in this compiler is incomplete, but this was the first time xrootd failed to build because of that.
I don't know if building only with the subset of C++14 supported by the default RHEL 7 compiler is expected to work, but until now it did work. Though that might have been just accidental.

[simonmichal]

Our strategy is now to use devtoolset-7 on RHEL7 platforms. AFAIK this is compatible with EPEL / Fedora, isn't it?

[simonmichal]

@ellert : I will merge this as this is minor change and I suppose it will make your life easier, that said be prepared that we might use C++14 features (e.g. make_unique, lambda capture expression, etc.)