test: Clear out old mocks prior to testing

This ensures we don't have stale mock data left over after each run
that will leak into unrelated tests.

Change-Id: I08bc12f99f1103c5d3024bf90047105b221622a2
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/mock_syscall.hpp b/test/mock_syscall.hpp
index 4d934b3..74a693e 100644
--- a/test/mock_syscall.hpp
+++ b/test/mock_syscall.hpp
@@ -3,6 +3,10 @@
 
 #include <string>
 
+/** @brief Clears out the interfaces and IPs configured for mocking
+ */
+void mock_clear();
+
 /** @brief Adds the given interface and addr info
  *         into the ifaddr list.
  *  @param[in] name - Interface name.