declare EbmlDummy constructor in cpp file

[neheb]

Fixes compilation on GCC7-9 for some reason.

[neheb]

This was probably introduced with 8441376

[robUx4]

What is the compilation error ? The code is strictly the same. If there's an include missing we should add it.

[neheb]

It’s a linker error. It can’t figure out where to place the class for some reason.

[neheb]

#233 (comment)

[neheb]

ChatGPT's reaction:

The reason for this fix might be related to how templates and inline functions are handled across different GCC versions. Some older versions of GCC might have difficulty with certain constructs, and moving the implementation of the constructor from the header to the cpp file can resolve these issues.

Without more specific details about the linker error or the GCC version in question, it's challenging to pinpoint the exact reason. However, the common practice of moving constructor implementations from header files to cpp files is often used to address such issues with template and inline code across different compiler versions.