dpkg, libdpkg: Remove unused variable assignments

Warned-by: clang static analyzer

lib/dpkg/parse.c

@@ -638,7 +638,6 @@ parse_stanza(struct parsedb_state *ps, struct field_state *fs,
           break;
 
         parse_ungetc(c, ps);
-        c = '\n';
         blank_line = true;
       } else if (blank_line && !isspace(c)) {
         blank_line = false;

src/script.c

@@ -185,7 +185,6 @@ maintscript_set_exec_context(struct command *cmd, const char *fallback)
 		newcon = strdup(context_str(tmpcon));
 		if (newcon == NULL)
 			goto out;
-		rc = 0;
 	}
 
 	rc = setexeccon(newcon);