Rename ZipEntryName to ZipString

This is for https://android-review.googlesource.com/#/c/156771/.

Bug: 21957428
Change-Id: Ida30c28c0fff0b2dadddbdb1aa1999ae3250610b
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 1f00771..c7a6bc8 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -1159,7 +1159,7 @@
 
   ZipEntry entry;
 
-  if (FindEntry(handle, ZipEntryName(file_path), &entry) != 0) {
+  if (FindEntry(handle, ZipString(file_path), &entry) != 0) {
     // Entry was not found.
     close(fd);
     return -1;