linker: show the exact ABI rather than "32-bit"/"64-bit".

It's slightly less code for us to be more exact.

Change-Id: Id46cad39bf278e522b426e43aff77ae2e1c4bc4b
diff --git a/linker/linker_main.cpp b/linker/linker_main.cpp
index 2b230a8..0bc7003 100644
--- a/linker/linker_main.cpp
+++ b/linker/linker_main.cpp
@@ -333,11 +333,7 @@
 
   if (getenv("LD_SHOW_AUXV") != nullptr) ld_show_auxv(args.auxv);
 
-#if defined(__LP64__)
-  INFO("[ Android dynamic linker (64-bit) ]");
-#else
-  INFO("[ Android dynamic linker (32-bit) ]");
-#endif
+  INFO("[ Android dynamic linker (" ABI_STRING ") ]");
 
   // These should have been sanitized by __libc_init_AT_SECURE, but the test
   // doesn't cost us anything.