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
diff --git a/cc/config/global.go b/cc/config/global.go
index 989c7ee..051eba5 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -87,12 +87,20 @@
 		"-Wl,--no-undefined-version",
 	}
 
+	deviceGlobalLldflags = append(ClangFilterUnknownLldflags(deviceGlobalLdflags),
+		[]string{
+			"-Wl,--pack-dyn-relocs=android",
+			"-fuse-ld=lld",
+		}...)
+
 	hostGlobalCflags = []string{}
 
 	hostGlobalCppflags = []string{}
 
 	hostGlobalLdflags = []string{}
 
+	hostGlobalLldflags = []string{}
+
 	commonGlobalCppflags = []string{
 		"-Wsign-promo",
 	}
@@ -141,9 +149,11 @@
 	pctx.StaticVariable("DeviceGlobalCflags", strings.Join(deviceGlobalCflags, " "))
 	pctx.StaticVariable("DeviceGlobalCppflags", strings.Join(deviceGlobalCppflags, " "))
 	pctx.StaticVariable("DeviceGlobalLdflags", strings.Join(deviceGlobalLdflags, " "))
+	pctx.StaticVariable("DeviceGlobalLldflags", strings.Join(deviceGlobalLldflags, " "))
 	pctx.StaticVariable("HostGlobalCflags", strings.Join(hostGlobalCflags, " "))
 	pctx.StaticVariable("HostGlobalCppflags", strings.Join(hostGlobalCppflags, " "))
 	pctx.StaticVariable("HostGlobalLdflags", strings.Join(hostGlobalLdflags, " "))
+	pctx.StaticVariable("HostGlobalLldflags", strings.Join(hostGlobalLldflags, " "))
 	pctx.StaticVariable("NoOverrideGlobalCflags", strings.Join(noOverrideGlobalCflags, " "))
 
 	pctx.StaticVariable("CommonGlobalCppflags", strings.Join(commonGlobalCppflags, " "))