Remove USE_CLANG_LLD[=false]

This should always be true now. It will be a change for side branches
(build_tools, etc) that weren't setting UseClangLld in the
soong.variables file.

Test: treehugger
Change-Id: I9fd6157fda630bf8bb939677dbcb026f02685f19

cc/linker.go

@@ -289,7 +289,7 @@ func (linker *baseLinker) useClangLld(ctx ModuleContext) bool {
 	if linker.Properties.Use_clang_lld != nil {
 		return Bool(linker.Properties.Use_clang_lld)
 	}
-	return ctx.Config().UseClangLld()
+	return true
 }
 
 // ModuleContext extends BaseModuleContext

cc/lto.go

@@ -76,7 +76,7 @@ func (lto *lto) useClangLld(ctx BaseModuleContext) bool {
 	if lto.Properties.Use_clang_lld != nil {
 		return Bool(lto.Properties.Use_clang_lld)
 	}
-	return ctx.Config().UseClangLld()
+	return true
 }
 
 func (lto *lto) flags(ctx BaseModuleContext, flags Flags) Flags {