gsk: Make shader matrices match

We were using slightly different numbers here, which isn't good.

The matrices in gdkcolordefs.h are tested in the colorstate-internal
tests, so they are at least properly inverse, and the products match.

It would be better to generate the glsl definitions, somehow.

gsk/gpu/shaders/color.glsl

@@ -99,15 +99,15 @@ pq_oetf (float v)
 /* Note that these matrices are transposed from the C version */
 
 const mat3 srgb_from_rec2020 = mat3(
-  1.659944, -0.124350, -0.018466,
-  -0.588220, 1.132559, -0.102459,
-  -0.071724, -0.008210, 1.120924
+  1.660227, -0.124553, -0.018155,
+ -0.587548,  1.132926, -0.100603,
+ -0.072838, -0.008350, 1.118998
 );
 
 const mat3 rec2020_from_srgb = mat3(
-  0.627610, 0.069029, 0.016649,
-  0.329815, 0.919817, 0.089510,
-  0.042574, 0.011154, 0.893842
+  0.627504, 0.069108, 0.016394,
+  0.329275, 0.919519, 0.088011,
+  0.043303, 0.011360, 0.895380
 );
 
 vec3

gsk/gpu/shaders/gskgpuconvertcicp.glsl

@@ -31,21 +31,21 @@ const mat3 identity = mat3(
 );
 
 const mat3 srgb_to_xyz = mat3(
- 0.4125288, 0.2127102, 0.0193373,
- 0.3581642, 0.7163284, 0.1193881,
- 0.1774037, 0.0709615, 0.9343260
+  0.4124564, 0.2126729, 0.0193339,
+  0.3575761, 0.7151522, 0.1191920,
+  0.1804375, 0.0721750, 0.9503041
 );
 
 const mat3 xyz_to_srgb = mat3(
-  3.2409699, -0.9692436,  0.0556301,
- -1.5373832,  1.8759675, -0.2039770,
- -0.4986108,  0.0415551,  1.0569715
+  3.2404542, -0.9692660,  0.0556434,
+ -1.5371385,  1.8760108, -0.2040259,
+ -0.4985314,  0.0415560,  1.0572252
 );
 
 const mat3 rec2020_to_xyz = mat3(
- 0.6369615, 0.2627016, 0.0000000,
- 0.1448079, 0.6788934, 0.0281098,
- 0.1663273, 0.0584050, 1.0449416
+  0.6369580, 0.2627002, 0.0000000,
+  0.1446169, 0.6779981, 0.0280727,
+  0.1688810, 0.0593017, 1.0609851
 );
 
 const mat3 xyz_to_rec2020 = mat3(