shebangfix: allow to use SHEBANG_REGEX, SHEBANG_GLOB and SHEBANG_FILES simultaneously

[AMDmi3]

Summary

A need to fix shebangs in a lot of files is common, and it's also
not uncommon to have to fix several classes of files simultaneously,
for example *.py everywhere in WRKSRC and also all files in scripts/.
For this purpose, one needs to use SHEBANG_GLOB and SHEBANG_FILES at
the same time, while code does not currently allow that. Let's fix this.

[mat]

I often wondered if there would be cases where one would need more than one.