Simmilar to gcc, the list of pre-processor defines can be fetched with
`-dM -E` option. The way cpu_family is determined on linux relies on
this list.
Fixes incorrect value of cpu_family on linux, when crosscompiling:
```
CC="clang -m32" meson ./build
```
Signed-off-by: Yevhenii Kolesnikov <yevhenii.kolesnikov@globallogic.com>
Co-authored-by: Dylan Baker <dylan@pnwbakers.com>
D lang compilers have an option -release (or similar) which turns off
asserts, contracts, and other runtime type checking. This patch wires
that up to the b_ndebug flag.
Fixes#7082
Clang supports the GCC -Og flag, but --optimization=g is not setting that. This is because Clang is referencing the clike_optimization_args, which does not define a flag for 'g'.
To address this, we'll mimic the GNU options instead of the C-like ones.
Fixes#6619
Now that the linkers are split out of the compilers this enum is
only used to know what platform we're compiling for. Which is
what the MachineInfo class is for