Feature request: Provide convenience macros for the names

I would like to propose providing the name of a detected component in a universal macro.

- `BOOST_LANG_NAME` shall be defined as detected language name
- `BOOST_ARCH_NAME` shall be defined as detected architecture name
and so on for `BOOST_COMP_NAME`, `BOOST_LIB_C_NAME`, `BOOST_LIB_STD_NAME`, `BOOST_LIB_OS_NAME`, maybe for `BOOST_PLAT_NAME`.

The primary use case of this proposal is conveniently printing some build information to the user, allowing better bug reports.

I understand that some of those definitions are ambiguous, for example `BOOST_ARCH_NAME` could be defined to either `BOOST_ARCH_X86_NAME` or `BOOST_ARCH_X86_64_NAME` on x86-64.
In these cases, I would propose using either the 'leaf' names which are the most specific or the first ones detected.