Add symlink for readlink(1).

Test: clean build
Change-Id: I56417a63545d11e5df724e6171b9ad43d852c929
diff --git a/toybox/linux-x86/readlink b/toybox/linux-x86/readlink
new file mode 120000
index 0000000..c6b4b1f
--- /dev/null
+++ b/toybox/linux-x86/readlink
@@ -0,0 +1 @@
+../../linux-x86/bin/toybox
\ No newline at end of file