internal/srgb: move app/internal/srgb

We're about to move app/headless to gpu/headless, and it imports
package srgb indirectly.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/egl/egl.go

@@ -10,9 +10,9 @@ import (
 	"runtime"
 	"strings"
 
-	"gioui.org/app/internal/srgb"
 	"gioui.org/gpu"
 	"gioui.org/internal/glimpl"
+	"gioui.org/internal/srgb"
 )
 
 type Context struct {

app/internal/window/gl_js.go

@@ -6,7 +6,7 @@ import (
 	"errors"
 	"syscall/js"
 
-	"gioui.org/app/internal/srgb"
+	"gioui.org/internal/srgb"
 	"gioui.org/gpu"
 	"gioui.org/internal/glimpl"
 )