How to fix redefinition error in GCC?

Question

C++ / C#

I'm trying to compile the old code for subsequent refactoring,
the error "(path to file) here is the re-definition of "verbosity"; build/TL/tlc-new.o:/home/user/stack/sowilo/TL/tlc-new.c: 48: here is the first definition

I have GCC 11.2.0
And I tried to specify the -fcommon flag in CFLAGS, but it didn't work,

here is my Makefile, please help me fix this error
https://pastebin.com/i1ykjJVG