Allow specifying exe suffix of cross host machine

[Jan200101]

implements #9857

adds support for an optional exe_suffix field in the host_machine section of cross file
that property will then end up being used as the executable suffix.

the name_suffix property of executable() will override this just like it overwrote the default suffix.

Here is the cross file I've used to test this:

[binaries]
c = 'gcc'

[host_machine]
system = 'linux'
cpu_family = 'x86_64'
cpu = 'x86'
endian = 'little'
exe_suffix = 'bla'

[jpakkane]

Are there use cases other than Emscripten? Because if that is the only user it seems to me that it could be solved better by having a wasm-specific option somehow. Meson needs to know that those additional files are also created for things like install to work.

[Jan200101]

I can't think of one off the top of my head (I will amend this if I can think of any) but I think having this, regardless of if wasm gets more specialized options, would be useful for foreign systems that meson may not officially support.

One use case I can think of for that would be homebrew toolchains, where its common to process the resulting elf file into system specific package.
There it would be very useful to specify the executable extension to be elf instead of none at all without having to specify it in the executable() call

[dcbaker]

Off the top of my head binaries run by UEFI firmware have the .efi extension, and unless someone has gotten really productive you cannot have the UEFI environment as a build environment, only as a host.