libc: Close all pipe file descriptors in popen() after dup2() is called

libc/src/stdio.cpp

@@ -793,11 +793,13 @@ extern "C"
             {
                 close(pfds[0]);
                 dup2(pfds[1], STDOUT_FILENO);
+                close(pfds[1]);
             }
             else
             {
                 close(pfds[1]);
                 dup2(pfds[0], STDIN_FILENO);
+                close(pfds[0]);
             }
 
             execl("/bin/sh", "sh", "-c", command, nullptr);