Fix cross-compilation of D programs

Since version 9.1, GCC provides support for the D programming language. Thus it
is easy to build a cross-compiler for D, such as aarch64-unknown-linux-gnu-gdc.

However to cross-compile a Meson project using D, using a cross build definition
such as the following is not enough:

```
[binaries]
d = '/path/to/aarch64-unknown-linux-gnu-gdc'
exe_wrapper = '/path/to/qemu-aarch64-static'

[properties]
needs_exe_wrapper = true

[host_machine]
system = 'linux'
cpu_family = 'aarch64'
cpu = 'cortex-a53'
endian = 'little'
```

Indeed, "exe_wrapper" is not be taken into account. Build will fail with:

```
Executables created by D compiler /path/to/aarch64-uknown-linux-gnu-gdc are not runnable.
```

This patch fixes this by reworking:

- detect_d_compiler() to properly get exe_wrapper and D compilers and detect the
one available.
- Dcompiler to properly handle exe_wrapper.

0 files changed, 0 insertions, 0 deletions