Fix build warnings introduced by the newterm patch

This commit fixes the following build warnings that have been introduced by the newterm patch: ``` patch/newterm.c:26:33: warning: ignoring return value of ‘chdir’ declared with attribute ‘warn_unused_result’ [-Wunused-result] 26 | chdir(get_foreground_cwd()); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ patch/newterm.c:28:33: warning: ignoring return value of ‘chdir’ declared with attribute ‘warn_unused_result’ [-Wunused-result] 28 | chdir(getcwd_by_pid(pid)); | ^~~~~~~~~~~~~~~~~~~~~~~~~ ```