app/internal/wm: rename confusing app/internal/window

Package wm (for "window manager") is a better fit for the package, and
distinguishes it from the low-level package windows for the Windows API.

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

app/internal/wm/runmain.go

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// +build android darwin,ios
+
+package wm
+
+// Android only supports non-Java programs as c-shared libraries.
+// Unfortunately, Go does not run a program's main function in
+// library mode. To make Gio programs simpler and uniform, we'll
+// link to the main function here and call it from Java.
+
+import (
+	"sync"
+	_ "unsafe" // for go:linkname
+)
+
+//go:linkname mainMain main.main
+func mainMain()
+
+var runMainOnce sync.Once
+
+func runMain() {
+	runMainOnce.Do(func() {
+		// Indirect call, since the linker does not know the address of main when
+		// laying down this package.
+		fn := mainMain
+		fn()
+	})
+}