ignoring return value of fread

[andreasstieger]

New werror in 3.0.0:

[   13s] /home/abuild/rpmbuild/BUILD/libbbf-3.0.0-build/libbbf-3.0.0/src/muxer/bbfmux.cpp: In function ‘char* readTxtFile(const char*)’:
[   13s] /home/abuild/rpmbuild/BUILD/libbbf-3.0.0-build/libbbf-3.0.0/src/muxer/bbfmux.cpp:71:10: error: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’ declared with attribute ‘warn_unused_result’ [-Werror=unused-result]
[   13s]    71 |     fread(cString, 1, fileSize, file);
[   13s]       |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
[   13s] cc1plus: all warnings being treated as errors
[   13s] make[2]: *** [CMakeFiles/bbfmux.dir/build.make:82: CMakeFiles/bbfmux.dir/src/muxer/bbfmux.cpp.o] Error 1

In https://github.com/ef1500/libbbf/blob/v3.0.0/src/muxer/bbfmux.cpp#L71 you are not checking the return value,