Compile issues

[ktb92677]

I receive the following error when compiling when I set ZR_COMPILE_WITH_VERTEX_BUFFER and
ZR_COMPILE_WITH_FONT to zero:

"/opt/lib/GUI/zahnrad.c: In function ‘zr_uint zr_color32(zr_color)’:
/opt/lib/GUI/zahnrad.c:363:20: error: ‘zr_draw_vertex_color’ was not declared in this scope
/opt/lib/GUI/zahnrad.c:363:41: error: expected ‘,’ or ‘;’ before ‘in’
/opt/lib/GUI/zahnrad.c:364:35: error: expected ‘)’ before ‘in’
/opt/lib/GUI/zahnrad.c:365:35: error: expected ‘)’ before ‘in’
/opt/lib/GUI/zahnrad.c:366:35: error: expected ‘)’ before ‘in’"