swscale/range_convert: saturate output instead of limiting input
For bit depths <= 14, the result is saturated to 15 bits.
For bit depths > 14, the result is saturated to 19 bits.
x86_64:
chrRangeFromJpeg8_1920_c: 2126.5 2127.4 (1.00x)
chrRangeFromJpeg16_1920_c: 2331.4 2325.2 (1.00x)
chrRangeToJpeg8_1920_c: 3163.0 3166.9 (1.00x)
chrRangeToJpeg16_1920_c: 3163.7 2152.4 (1.47x)
lumRangeFromJpeg8_1920_c: 1262.2 1263.0 (1.00x)
lumRangeFromJpeg16_1920_c: 1079.5 1080.5 (1.00x)
lumRangeToJpeg8_1920_c: 1860.5 1886.8 (0.99x)
lumRangeToJpeg16_1920_c: 1910.2 1077.0 (1.77x)
aarch64 A55:
chrRangeFromJpeg8_1920_c: 28836.2 28835.2 (1.00x)
chrRangeFromJpeg16_1920_c: 28840.1 28839.8 (1.00x)
chrRangeToJpeg8_1920_c: 44196.2 23074.7 (1.92x)
chrRangeToJpeg16_1920_c: 36527.3 17318.9 (2.11x)
lumRangeFromJpeg8_1920_c: 15388.5 15389.7 (1.00x)
lumRangeFromJpeg16_1920_c: 15389.3 15388.2 (1.00x)
lumRangeToJpeg8_1920_c: 23069.7 19227.8 (1.20x)
lumRangeToJpeg16_1920_c: 19227.8 15387.0 (1.25x)
aarch64 A76:
chrRangeFromJpeg8_1920_c: 6334.7 6324.4 (1.00x)
chrRangeFromJpeg16_1920_c: 6336.0 6339.9 (1.00x)
chrRangeToJpeg8_1920_c: 11474.5 9656.0 (1.19x)
chrRangeToJpeg16_1920_c: 9640.5 6340.4 (1.52x)
lumRangeFromJpeg8_1920_c: 4453.2 4422.0 (1.01x)
lumRangeFromJpeg16_1920_c: 4414.2 4420.9 (1.00x)
lumRangeToJpeg8_1920_c: 6645.0 5949.1 (1.12x)
lumRangeToJpeg16_1920_c: 6005.2 4446.8 (1.35x)
NOTE: all simd optimizations for range_convert have been disabled
except for x86, which already had the same behaviour.
they will be re-enabled when they are fixed for each architecture.