VersionTracker: Ignore libraries without soname

Bug: http://b/20872443
Change-Id: I7bd076885c1feae39af6ea64c9442bcc5ae5a1dc
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 2669a56..a6b480c 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -1701,7 +1701,7 @@
     const char* target_soname = si_from->get_string(verneed->vn_file);
     // find it in dependencies
     soinfo* target_si = si_from->get_children().find_if([&](const soinfo* si) {
-      return strcmp(si->get_soname(), target_soname) == 0;
+      return si->get_soname() != nullptr && strcmp(si->get_soname(), target_soname) == 0;
     });
 
     if (target_si == nullptr) {