Rename misleading define

The macro USE_LIGHT_SHADOW_COLOR actually was being defined when the shader used SHADOW (the output shadow color), not the shadow color set for the light so it's better named USE_OUTPUT_SHADOW_COLOR. In 3D there's not that difference but renaming as well for consistency.

drivers/gles2/rasterizer_gles2.cpp

@@ -4666,7 +4666,7 @@ void RasterizerGLES2::_update_shader( Shader* p_shader) const {
 			enablers.push_back("#define USE_LIGHT_SHADER_CODE\n");
 		}
 		if (light_flags.uses_shadow_color) {
-			enablers.push_back("#define USE_LIGHT_SHADOW_COLOR\n");
+			enablers.push_back("#define USE_OUTPUT_SHADOW_COLOR\n");
 		}
 		if (light_flags.uses_time || fragment_flags.uses_time || vertex_flags.uses_time) {
 			enablers.push_back("#define USE_TIME\n");
@@ -4709,7 +4709,7 @@ void RasterizerGLES2::_update_shader( Shader* p_shader) const {
 			enablers.push_back("#define USE_TEXPIXEL_SIZE\n");
 		}
 		if (light_flags.uses_shadow_color) {
-			enablers.push_back("#define USE_LIGHT_SHADOW_COLOR\n");
+			enablers.push_back("#define USE_OUTPUT_SHADOW_COLOR\n");
 		}
 
 		if (vertex_flags.uses_worldvec) {

drivers/gles2/shaders/canvas.glsl

@@ -244,7 +244,7 @@ FRAGMENT_SHADER_CODE
 
 	vec2 light_uv = light_uv_interp.xy;
 	vec4 light = texture2D(light_texture,light_uv) * light_color;
-#if defined(USE_LIGHT_SHADOW_COLOR)
+#if defined(USE_OUTPUT_SHADOW_COLOR)
 	vec4 shadow_color=vec4(0.0,0.0,0.0,0.0);
 #endif
 
@@ -380,7 +380,7 @@ LIGHT_SHADER_CODE
 
 #endif
 
-#if defined(USE_LIGHT_SHADOW_COLOR)
+#if defined(USE_OUTPUT_SHADOW_COLOR)
 	color=mix(shadow_color,color,shadow_attenuation);
 #else
 	//color*=shadow_attenuation;

drivers/gles2/shaders/material.glsl

@@ -1181,7 +1181,7 @@ FRAGMENT_SHADER_CODE
 		vec3 mdiffuse = diffuse.rgb;
 		vec3 light;
 
-#if defined(USE_LIGHT_SHADOW_COLOR)
+#if defined(USE_OUTPUT_SHADOW_COLOR)
 		vec3 shadow_color=vec3(0.0,0.0,0.0);
 #endif
 
@@ -1205,7 +1205,7 @@ LIGHT_SHADER_CODE
 #endif
 		diffuse.rgb = const_light_mult * ambient_light *diffuse.rgb + light * attenuation * shadow_attenuation;
 
-#if defined(USE_LIGHT_SHADOW_COLOR)
+#if defined(USE_OUTPUT_SHADOW_COLOR)
 		diffuse.rgb += light * shadow_color * attenuation * (1.0 - shadow_attenuation);
 #endif