Fix "cannot bind non-const lvalue reference of type ‘ImVec4&’ to an rvalue of type ‘ImVec4’" compilation error

[brlin-tw]

This patch fixes the following compilation error on GCC 12 of the MinGW-w64 toolchain:

wkbre/wkbre.cpp: In function ‘bool IGPlayerChooser(char*, goref*)’:
wkbre/wkbre.cpp:2404:41: error: cannot bind non-const lvalue reference of type ‘ImVec4&’ to an rvalue of type ‘ImVec4’
 2404 |                 OldColorButton("color", ImVec4(1, 1, 1, 1));
      |                                         ^~~~~~~~~~~~~~~~~~
wkbre/wkbre.cpp:1900:47: note:   initializing argument 2 of ‘bool OldColorButton(const char*, ImVec4&, bool)’
 1900 | bool OldColorButton(const char *desc, ImVec4 &col, bool mini = false)
      |                                       ~~~~~~~~^~~

as the pass-by-reference syntax doesn't seem to be necessary. I have little to no C++/Dear ImGui experience so feel free to close this if it's not the case.

[AdrienTD]

The best would have been to use const ImVec4&. This will allow "temporaries" (objects constructed inside a function call argument) to be used. And it would avoid a copy of the entire ImVec4 (though it might be true that in case of temporaries, there is no copy).

But yeah, I made this a while ago when I just started to use C++, hence why there is a lot of bad code and style. (and using the -fpermissive compiler option is something somebody should never use).

[brlin-tw]

@AdrienTD:

The best would have been to use const ImVec4&. This will allow "temporaries" (objects constructed inside a function call argument) to be used. And it would avoid a copy of the entire ImVec4 (though it might be true that in case of temporaries, there is no copy).

Thanks for the guidance, I've updated the branch to include the proper code fix, please review.