Including both sys/prctl.h and linux/prctl.h fails on linux due to duplicate struct prctl_mm_map

[TimEvens]

picoquic/picoquic/sockloop.c

Line 83 in 6fc1ff2

#include <linux/prctl.h> /* Definition of PR_* constants */

struct prctl_mm_map is defined in both linux/prctl.h and sys/prctl.h. This breaks builds due to the duplicate. It appears only one needs to be included. Suggest the below fix...

#ifndef __APPLE__
#ifdef __LINUX__
#include <linux/prctl.h>  /* Definition of PR_* constants */
#else
#include <sys/prctl.h>
#endif
#endif

[huitema]

@TimEvens Thanks for the report. I pushed your suggested changes in PR #1768.