My mistake, I did not notice it, but after I changed it, it still not working:
C:/TDM-GCC-64/bin/../lib/gcc/x86_64-w64-mingw32/5.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lsndfile-1
collect2.exe: error: ld returned 1 exit status
src\CMakeFiles\libfluidsynth.dir\build.make:151: recipe for target 'src/libfluidsynth-2.dll' failed
mingw32-make.exe[2]: *** [src/libfluidsynth-2.dll] Error 1
CMakeFiles\Makefile2:95: recipe for target 'src/CMakeFiles/libfluidsynth.dir/all' failed
mingw32-make.exe[1]: *** [src/CMakeFiles/libfluidsynth.dir/all] Error 2
Makefile:150: recipe for target 'all' failed
mingw32-make.exe: *** [all] Error 2