meson: remove -std=c++11 from intel/tools

meson: remove -std=c++11 from intel/tools

for meson all C++ code is already compiled as C++11, so it's
unnecessary. It's also the wrong way to do this, if we really needed
this the correct way is to set:

```meson
executable(
  ...
  override_options : ['cpp_std=c++11'],
)
```

Which ensures not only that the correct syntax for the current
compiler is used, but also that meson doesn't create arguments like
`-std=c++14 ... -std=c++11`

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>