Fix T97983 EEVEE: Tangent Normal of Curves info behaves differently in Eevee

Curve tangent was correctly mistaken with curve normal.

This patch fixes the name of the output in the glsl function and make curve
attributes more explicit (with `curve_` prefix).

This also improve the normal computation by making it per pixel to match
cycles.

Also ports the changes to eevee-next.

source/blender/draw/engines/eevee/shaders/surface_lib.glsl

@@ -112,6 +112,7 @@ GlobalData init_globals(void)
     surf.N = -surf.N;
   }
 #  ifdef HAIR_SHADER
+  vec3 V = cameraVec(surf.P);
   /* Shade as a cylinder. */
   vec3 B = normalize(cross(worldNormal, hairTangent));
   float cos_theta;
@@ -125,7 +126,10 @@ GlobalData init_globals(void)
   }
   float sin_theta = sqrt(max(0.0, 1.0 - cos_theta * cos_theta));
   surf.N = safe_normalize(worldNormal * sin_theta + B * cos_theta);
-  surf.T = hairTangent;
+  surf.curve_T = -hairTangent;
+  /* Costly, but follows cycles per pixel tangent space (not following curve shape). */
+  surf.curve_B = cross(V, surf.curve_T);
+  surf.curve_N = safe_normalize(cross(surf.curve_T, surf.curve_B));
   surf.is_strand = true;
   surf.hair_time = hairTime;
   surf.hair_thickness = hairThickness;
@@ -134,7 +138,7 @@ GlobalData init_globals(void)
   surf.barycentric_coords = hair_resolve_barycentric(hairBary);
 #    endif
 #  else
-  surf.T = vec3(0.0);
+  surf.curve_T = surf.curve_B = surf.curve_N = vec3(0.0);
   surf.is_strand = false;
   surf.hair_time = 0.0;
   surf.hair_thickness = 0.0;