Merge "Revert^3 "Enable full LTO optimization by default"" into main

	// Use -fwhole-program-vtables cflag.

	Whole_program_vtables *bool

	// Use --lto-O0 flag.

	Lto_O0 *bool

}

type lto struct {

		ltoCFlags := []string{"-flto=thin", "-fsplit-lto-unit"}

		var ltoLdFlags []string

		// Do not perform costly LTO optimizations for Eng builds.

		if Bool(lto.Properties.Lto_O0) || ctx.Config().Eng() {

		// The module did not explicitly turn on LTO. Only leverage LTO's

		// better dead code elimination and CFG simplification, but do

		// not perform costly optimizations for a balance between compile

		// time, binary size and performance.

		// Apply the same for Eng builds as well.

		if !lto.ThinLTO() || ctx.Config().Eng() {

			ltoLdFlags = append(ltoLdFlags, "-Wl,--lto-O0")

		}