The `check_type_size(ssize_t SIZEOF_SSIZE_T` call in cmcurl (referenced
by the comment above) defines `HAVE_SIZEOF_SSIZE_T` and not
`HAVE_SSIZE_T`. The `HAVE_SSIZE_T` variable *might* get defined, but
via the `CHECK_TYPE_SIZE(ssize_t SSIZE_T)` call in cmlibarchive, which
would be configured *after* cmnghttp2, and so the first configure would
lead to an invalid `cmnghttp2/config.h` file.
Divert LCC compiler as a new one, instead of treating it as GNU.
Since old times, Elbrus C/C++/Fortran Compiler (LCC) by MCST has been
passing checks for GNU compilers, so it has been identified as GNU.
Now, with intent of seriously upstreaming its support, it has been
added as a separate LCC compiler, and its version displays not a
supported GCC version, but LCC version itself (e.g. LCC 1.25.19 instead
of GNU 7.3.0).
This commit adds its support for detection, and also converts basically
every check like 'is this compiler GNU?' to 'is this compiler GNU or
LCC?'. The only places where this check is untouched, is where it
regards other platforms where LCC is unavailable (primarily non-Linux),
and where it REALLY differs from GNU compiler.
Note: this transition may break software that are already ported to
Elbrus, but hardly relies that LCC will be detected as GNU; still such
software is not known.
Provide our own minimal `config.h` since the upstream one is much
larger to support other parts of its distribution. Compile with
warnings disabled since this is third-party code.
