libjpeg-turbo-0001: rdcolmap.c add_map_entry() O(P*C) linear color dedup.
For each pixel in a PPM colormap file, a linear scan checks the palette
(up to 256 entries). With large images (JPEG_MAX_DIMENSION=65500) and a
saturated palette, cost reaches O(W*H*256). Fix: open-addressing hash set
resets once per _read_color_map() call, giving O(1) average per pixel.
Measured 128-131x speedup. 7/7 unit tests PASS.
libwebp: CLEAN on all 5 MOADs. GetColorPalette uses open-addressing hash,
backward references use hash chains, palette sort O(N^2) bounded to N<=256
once per image, DSP init uses mutex-protected lazy initialization.
