How to suppress all warnings being treated as errors for format-truncation

Depending on the makefile, you probably need something like:

make CFLAGS="-Wno-error=format-truncation"

The default Makefile rules, and most well-written Makefiles, should see CFLAGS for option arguments to the C compiler being used. Similarly, you can use CXXFLAGS for providing options to the C++ compiler, and LDFLAGS for the linker.