[loader] update non-sdk loader target name

This change updates the target name of the loader library on linux. This
allows it to be unconditionally included by ../vulkan.

Test: CQ, built dependent fuchsia changes locally
Change-Id: I52d3afaaea3a1fbc073cadffe934acc592942eea
diff --git a/loader/BUILD.gn b/loader/BUILD.gn
index c4d47a4..a9aba08 100644
--- a/loader/BUILD.gn
+++ b/loader/BUILD.gn
@@ -122,7 +122,7 @@
 }
 
 if (is_linux) {
-  shared_library("loader_lib") {
+  shared_library("loader") {
     # The Vulkan loader is named libvulkan
     output_name = "vulkan"
     deps = [