Remove the apparently unused LibraryToLink#isSolibSymlink() method.

--
MOS_MIGRATED_REVID=121472172
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java
index d5e338b..c394181 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java
@@ -110,11 +110,6 @@
    * has a library identifier.
    */
   public interface LibraryToLink extends LinkerInput {
-    /**
-     * Returns whether the library is a solib symlink.
-     */
-    boolean isSolibSymlink();
-
     Iterable<Artifact> getLTOBitcodeFiles();
   }
 
@@ -170,11 +165,6 @@
     }
 
     @Override
-    public boolean isSolibSymlink() {
-      return true;
-    }
-
-    @Override
     public boolean equals(Object that) {
       if (this == that) {
         return true;
@@ -270,11 +260,6 @@
     public int hashCode() {
       return libraryArtifact.hashCode();
     }
-
-    @Override
-    public boolean isSolibSymlink() {
-      return false;
-    }
   }
 
   //////////////////////////////////////////////////////////////////////////////////////