Linux: silence UBSAN implicit conversions

pgrp and session might be -1

linux/LinuxProcessList.c:312:20: runtime error: implicit conversion from type 'unsigned long' of value 18446744073709551615 (64-bit, unsigned) to type 'unsigned int' changed the value to 4294967295 (32-bit, unsigned)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior linux/LinuxProcessList.c:312:20 in
linux/LinuxProcessList.c:314:23: runtime error: implicit conversion from type 'unsigned long' of value 18446744073709551615 (64-bit, unsigned) to type 'unsigned int' changed the value to 4294967295 (32-bit, unsigned)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior linux/LinuxProcessList.c:314:23 in

Process.h

@@ -76,10 +76,10 @@ typedef struct Process_ {
    pid_t tgid;
 
    /* Process group identifier */
-   unsigned int pgrp;
+   int pgrp;
 
    /* Session identifier */
-   unsigned int session;
+   int session;
 
    /* Foreground group identifier of the controlling terminal */
    int tpgid;

linux/LinuxProcessList.c

@@ -316,11 +316,11 @@ static bool LinuxProcessList_readStatFile(Process* process, openat_arg_t procFd,
    location += 1;
 
    /* (5) pgrp  -  %d */
-   process->pgrp = strtoul(location, &location, 10);
+   process->pgrp = strtol(location, &location, 10);
    location += 1;
 
    /* (6) session  -  %d */
-   process->session = strtoul(location, &location, 10);
+   process->session = strtol(location, &location, 10);
    location += 1;
 
    /* (7) tty_nr  -  %d */