Compilation error for compression mini app on OSX

[pramodk]

Hello,

When I try to compile mini app on OSX with Clang, I see :

[ 46%] Building CXX object neuromapp/keyvalue/CMakeFiles/MPI_Exec_kv.dir/mpiexec.cpp.o
In file included from /Users/kumbhar/Downloads/neuromapp/test/compression/block_reading.cpp:16:
/Users/kumbhar/Downloads/neuromapp/neuromapp/compression/allocator.h:105:13: error: unknown type name 'constexpr'
            constexpr static char policy_name[] = "cstandard";
            ^
/Users/kumbhar/Downloads/neuromapp/neuromapp/compression/allocator.h:105:23: error: expected member name or ';' after declaration specifiers
            constexpr static char policy_name[] = "cstandard";
            ~~~~~~~~~ ^
/Users/kumbhar/Downloads/neuromapp/neuromapp/compression/allocator.h:49:88: error: use of enumeration in a nested name specifier is a C++11 extension
      [-Werror,-Wc++11-extensions]
                    throw cpu_memory_allocation("negative size, cpu cstandard policy", lengine_error::NEUROMAPP_BAD_ARG);
                                                                                       ^
/Users/kumbhar/Downloads/neuromapp/neuromapp/compression/allocator.h:51:84: error: use of enumeration in a nested name specifier is a C++11 extension
      [-Werror,-Wc++11-extensions]
                    throw cpu_memory_allocation("null size, cpu cstandard policy", lengine_error::NEUROMAPP_BAD_ARG);
                                                                                   ^
/Users/kumbhar/Downloads/neuromapp/neuromapp/compression/allocator.h:201:13: error: unknown type name 'constexpr'
            constexpr static char policy_name[] = "align";
            ^
/Users/kumbhar/Downloads/neuromapp/neuromapp/compression/allocator.h:201:23: error: expected member name or ';' after declaration specifiers

In #84 I will just update README with this.

[jplanasc]

This mini-app has a lot of issues and should not have been merged in its current state.
Related to this issue, it does not follow the naming convention of the other mini-apps to enable/disable them. When building, -DNEUROMAPP_DISABLE_COMPRESSION=TRUE should be set in order to disable this mini-app.
In addition, the mini-app should be able to detect when its compilation will fail and disable itself automatically, like the other mini-apps do.