Add toybox to the default manifest.

default.xml

@@ -266,6 +266,7 @@
   <project path="external/tinycompress" name="platform/external/tinycompress" groups="pdk" />
   <project path="external/tinyxml" name="platform/external/tinyxml" groups="pdk" />
   <project path="external/tinyxml2" name="platform/external/tinyxml2" groups="pdk" />
+  <project path="external/toybox" name="platform/external/toybox" groups="pdk" />
   <project path="external/tremolo" name="platform/external/tremolo" groups="pdk" />
   <project path="external/valgrind" name="platform/external/valgrind" groups="pdk" />
   <project path="external/vixl" name="platform/external/vixl" groups="pdk" />