Add USE_CLANG_LLD and use_clang_lld.

* USE_CLANG_LLD is unedefined in current builds.
* When USE_CLANG_LLD is defined to 'true' or '1',
  use clang's lld instead of ld or ld.gold.
* When lld is enabled:
  * ld-only flags are not passed to 'lld'.
  * location_packer is disabled.
  * Use new lld's --pack-dyn-relocs=android.
* When lld does not work:
  * In Android.mk files use LOCAL_USE_CLANG_LLD := false.
  * In Android.bp files use use_clang_lld: false.
* Only arm, arm64, x86, and x86_64_devices have LLD flags;
  all other hosts and targets do not call lld yet.

Bug: 73768157
Test: make checkbuild and boot
Change-Id: I06b8a1e868a600997a7e70fe05c299d751d23d5f

cc/relocation_packer.go

@@ -38,12 +38,22 @@ type RelocationPackerProperties struct {
 	// This will be true even if we're embedded in Make, in which case
 	// we'll defer to make to actually do the packing.
 	PackingRelocations bool `blueprint:"mutated"`
+
+	// Use clang lld instead of gnu ld.
+	Use_clang_lld *bool
 }
 
 type relocationPacker struct {
 	Properties RelocationPackerProperties
 }
 
+func (p *relocationPacker) useClangLld(ctx BaseModuleContext) bool {
+	if p.Properties.Use_clang_lld != nil {
+		return Bool(p.Properties.Use_clang_lld)
+	}
+	return ctx.Config().UseClangLld()
+}
+
 func (p *relocationPacker) packingInit(ctx BaseModuleContext) {
 	enabled := true
 	// Relocation packer isn't available on Darwin yet
@@ -56,6 +66,11 @@ func (p *relocationPacker) packingInit(ctx BaseModuleContext) {
 	if ctx.Config().Getenv("DISABLE_RELOCATION_PACKER") == "true" {
 		enabled = false
 	}
+	// Relocation packer does not work with lld output files.
+	// Packed files won't load.
+	if p.useClangLld(ctx) {
+		enabled = false
+	}
 	if ctx.useSdk() {
 		enabled = false
 	}