Symlink llvm-dlltool -> llvm-ar

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

Change-Id: I92346dbd4db87254245422aa479b1613463abff4
diff --git a/clang-r487747c/bin/llvm-dlltool.exe b/clang-r487747c/bin/llvm-dlltool.exe
new file mode 120000
index 0000000..dd90184
--- /dev/null
+++ b/clang-r487747c/bin/llvm-dlltool.exe
@@ -0,0 +1 @@
+llvm-ar.exe
\ No newline at end of file