Revert "libsmooth: findkey: Empty target string if key could not be found."

This reverts commit 0add8f90ae.

src/install+setup/libsmooth/varval.c

@@ -151,9 +151,6 @@ int findkey(struct keyvalue *head, char *key, char *value)
 		cur = cur->next;
 	}
 
-	// Empty value if we could not find key.
-	value[0] = '\0';
-
 	return 0;
 }