initialize likely_colormap_index

[mateoconlechuga]

This is needed to avoid uninitialized usage later on, which is reported by valgrind as shown below. It seemed like the best place to put it, but I would just like to make sure. Thanks!

==11283== Conditional jump or move depends on uninitialised value(s)
==11283==    at 0x13D99C: pngquant_quantize (libimagequant.c:2000)
==11283==    by 0x1384B8: liq_histogram_quantize_internal (libimagequant.c:1018)
==11283==    by 0x138334: liq_image_quantize (libimagequant.c:992)
==11283==    by 0x138249: liq_quantize_image (libimagequant.c:970)
==11283==    by 0x12679B: image_quantize (image.c:486)
==11283==    by 0x126BA8: main (main.c:92)
==11283== 
==11283== Use of uninitialised value of size 8
==11283==    at 0x141A9B: nearest_search (nearest.c:174)
==11283==    by 0x1355C6: kmeans_do_iteration (kmeans.c:85)
==11283==    by 0x13DAAC: pngquant_quantize (libimagequant.c:2015)
==11283==    by 0x1384B8: liq_histogram_quantize_internal (libimagequant.c:1018)
==11283==    by 0x138334: liq_image_quantize (libimagequant.c:992)
==11283==    by 0x138249: liq_quantize_image (libimagequant.c:970)
==11283==    by 0x12679B: image_quantize (image.c:486)
==11283==    by 0x126BA8: main (main.c:92)
==11283== 
==11283== Use of uninitialised value of size 8
==11283==    at 0x141D4D: nearest_search (nearest.c:175)
==11283==    by 0x1355C6: kmeans_do_iteration (kmeans.c:85)
==11283==    by 0x13DAAC: pngquant_quantize (libimagequant.c:2015)
==11283==    by 0x1384B8: liq_histogram_quantize_internal (libimagequant.c:1018)
==11283==    by 0x138334: liq_image_quantize (libimagequant.c:992)
==11283==    by 0x138249: liq_quantize_image (libimagequant.c:970)
==11283==    by 0x12679B: image_quantize (image.c:486)
==11283==    by 0x126BA8: main (main.c:92)

[kornelski]

Thanks