net/addr/ether: Add FromStr conversion

Change-Id: I85ae2b914fa5a84d2acb103a61d78ce60ab9bef4
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/net/addr/ether.cpp b/src/net/addr/ether.cpp
index e50a2ff..5266733 100644
--- a/src/net/addr/ether.cpp
+++ b/src/net/addr/ether.cpp
@@ -1 +1,6 @@
 #include <stdplus/net/addr/ether.hpp>
+
+namespace stdplus
+{
+template EtherAddr FromStr<EtherAddr>::operator()(std::string_view) const;
+}