Fix fluid log

[carlo-bramini]

For people who wants to strip a bit the size of the binary, it is possible to reduce the size of the executable by commenting the content of the FLUID_LOG macro. However, I discovered that there are some points in the code that are calling directly the function fluid_log() instead of using FLUID_LOG macro. So, this patch fixes the sources that still need to replace fluid_log() with FLUID_LOG macro.

[derselbst]

You forgot the explanatory comment at the definition of the FLUID_LOG macro.

[carlo-bramini]

Sorry, I had understood that the explanatory comment had to be only in the GIT log. I will do it.

[derselbst]

Moving FLUID_LOG to fluid_sys.h breaks the unit tests. I would prefer to keep it in fluidsynth_priv.h. Also: Have you considered #define FLUID_LOG (void)sizeof?