Add PCX decoder support #1663

Job	Run time
Fuzz targets (afl)	2m 27s
Fuzz targets (cargo-fuzz)	1m 8s
cargo-deny	21s
build_benchmarks	48s
cargo-semver-checks	33s
clippy	2m 6s
public_private_dependencies	26s
rustfmt	14s
test_avif_decoding	1m 27s
test_features	29s
test_other_archs (powerpc-unknown-linux-gnu)	2m 33s
test_features (default)	1m 53s
test_toolchains (1.70.0)	32s
test_other_archs (i686-unknown-linux-gnu)	1m 18s
test_features (rayon)	29s
test_toolchains (nightly)	1m 48s
test_features (avif)	1m 7s
test_toolchains (beta)	1m 34s
test_features (bmp)	39s
test_features (dds)	28s
test_features (exr)	44s
test_features (ff)	25s
test_features (gif)	30s
test_features (hdr)	23s
test_features (ico)	30s
test_features (jpeg)	26s
test_features (pcx)	29s
test_features (png)	34s
test_features (pnm)	29s
test_features (qoi)	22s
test_features (tga)	29s
test_features (tiff)	37s
test_features (webp)	26s
	28m 44s

Provide feedback