Compilation fails on NixOS

[ThibaultLemaire]

../../../src/Game/File.c:1988:9: error: format not a string literal and no format arguments [-Werror=format-security]
         fprintf(file,str);
         ^~~~~~~
cc1: some warnings being treated as errors

libtool: 2.4.6
autoconf: 2.69
automake: 1.16.1
gnumake: 4.2.1
gcc: 7.4.0
yacc: 3.4.1
flex: 2.6.4
SDL: 2.0.9

[ThibaultLemaire]

Build still works on Arch Linux on the same commit.

libtool: 2.4.6.42-b88ce
autoconf: 2.69
automake: 1.16.1
gnumake: 4.2.1
gcc: 9.1.0
yacc: 3.4
flex: 2.6.4
SDL2: 2.0.10