Resolve "unused DT entry" warnings for x86_64

Change-Id: I3a2c87bf6e6259313cd9203389623f13b7405ef3
diff --git a/linker/linker.cpp b/linker/linker.cpp
index be2b45a..fc46172 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -1936,14 +1936,19 @@
           return false;
         }
         break;
-#if !defined(__LP64__)
       case DT_PLTREL:
-        if (d->d_un.d_val != DT_REL) {
-          DL_ERR("unsupported DT_RELA in \"%s\"", name);
+#if defined(USE_RELA)
+        if (d->d_un.d_val != DT_RELA) {
+          DL_ERR("unsupported DT_PLTREL in \"%s\"; expected DT_RELA", name);
           return false;
         }
-        break;
+#else
+        if (d->d_un.d_val != DT_REL) {
+          DL_ERR("unsupported DT_PLTREL in \"%s\"; expected DT_REL", name);
+          return false;
+        }
 #endif
+        break;
       case DT_JMPREL:
 #if defined(USE_RELA)
         plt_rela = reinterpret_cast<ElfW(Rela)*>(load_bias + d->d_un.d_ptr);
@@ -2120,6 +2125,11 @@
         mips_gotsym = d->d_un.d_val;
         break;
 #endif
+      case DT_VERSYM:
+      case DT_VERDEF:
+      case DT_VERDEFNUM:
+        // Ignore: bionic does not support symbol versioning...
+        break;
 
       default:
         if (!relocating_linker) {