common: Silence two discarded result warnings

These are intentionally discarded internally, since the rest of the
public API allows querying success. We want all non-internal uses of
these functions to be explicitly checked, so we can signify that we
intentionally want to discard the return values here.

src/common/dynamic_library.cpp

@@ -21,7 +21,7 @@ namespace Common {
 DynamicLibrary::DynamicLibrary() = default;
 
 DynamicLibrary::DynamicLibrary(const char* filename) {
-    Open(filename);
+    void(Open(filename));
 }
 
 DynamicLibrary::DynamicLibrary(DynamicLibrary&& rhs) noexcept