Remove has_DT_SYMBOLIC flag

  From the elf-spec: "Symbolically bound shared objects are
  identified by the .dynamic entry DT_SYMBOLIC. This tag is
  informational only; the runtime linker processes symbol
  lookups from these objects in the same manner as any
  other object."

Bug: 18186310

(cherry picked from commit 8f61d991831f0ea515fa50a5c38dbbcfbab0dd28)

Change-Id: I37024799ac8d1837993c8ae78780a448bedd6539
diff --git a/linker/linker.h b/linker/linker.h
index ef2fbcd..e395850 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -197,7 +197,7 @@
 #if !defined(__LP64__)
   bool has_text_relocations;
 #endif
-  bool has_DT_SYMBOLIC;
+  bool unused4; // DO NOT USE, maintained for compatibility
 
   soinfo(const char* name, const struct stat* file_stat, off64_t file_offset, int rtld_flags);