Symlink llvm-dlltool -> llvm-ar

Workaround until aosp/2623257 does this on a permanent basis.

Change-Id: I1902e44e20097d1abd80d6e69c31de488aef6c64
diff --git a/clang-r487747c/bin/llvm-dlltool b/clang-r487747c/bin/llvm-dlltool
new file mode 120000
index 0000000..3b94d1a
--- /dev/null
+++ b/clang-r487747c/bin/llvm-dlltool
@@ -0,0 +1 @@
+llvm-ar
\ No newline at end of file