Change the calling convention in sick_scan_xd_api_wrapper.c from __stdcall to __cdecl

[Sertzu]

This is a proposed solution to issue #310

Changing the calling convention from stdcall to cdecl here enables the library to operate in 32-bit mode. Since the .dll is also compiled with __cdecl as the calling convention this makes sense.

However, we weren't able to test if the library still works fine with real hardware though.

[rostest]

Thanks for your pull request, we appreciate your feedback and input. We will merge it by adding a customizable define to declare a specific calling convention. This way the calling convention can be set by a cmake flag, if required.

Calling conventions depend on the system; different architectures use different defaults. Calling conventions can be e.g.:

• "For the x86 architecture, the default calling convention is platform specific. Stdcall is the default calling convention on Windows x86 and it is used by most Win32 APIs. Cdecl is the default calling convention on Linux x86." (https://learn.microsoft.com/en-us/dotnet/standard/native-interop/calling-conventions)
• "On 32-bit Windows, operating system calls have the stdcall calling convention, whereas many C programs that run there use the cdecl calling convention." (https://en.wikipedia.org/wiki/Calling_convention)
• "The x64 Application Binary Interface (ABI) uses a four-register fast-call calling convention by default." (https://learn.microsoft.com/en-us/cpp/build/x64-calling-convention)
• "The keywords _stdcall and _cdecl specify 32-bit calling conventions. That's why they are not relevant for 64-bit programs (i.e. x64). On x64, there is only the standard calling convention and the extended __vectorcall calling convenction." (https://stackoverflow.com/questions/62746886/why-is-the-stdcall-calling-convention-ignored-in-x64)

We will therefore introduce a define (cmake flag), which can be overwritten if needed.