[lwp] Implementation of setpgrp and fix mmap2 problems (#9308)

* mmap2 failure handling

当传入一个非常大的地址时，offset会计算得到一个值，又因为传入的地址错误，rc会得到错误码，结合offset会得到一个很奇怪的值。

* Implementation of setpgrp

执行setpgrp会走到这一步，在执行getpgrp无法得到创建的group的值

* Modify the return method of mmap

Author: rcitach

Diff for: components/lwp/lwp_pgrp.c

@@ -403,6 +403,18 @@ sysret_t sys_setpgid(pid_t pid, pid_t pgid)
         if (group == RT_NULL)
         {
             group = lwp_pgrp_create(process);
+            lwp_pgrp_move(group, process);
+            session = lwp_session_find(sid);
+            if (session == RT_NULL)
+            {
+                LOG_E("the session of sid: %d cannot be found", sid);
+                err = -EPERM;
+                goto exit;
+            }
+            else
+            {
+                lwp_session_insert(session, group);
+            }
         }
         else
         {

Diff for: components/lwp/lwp_syscall.c

@@ -1229,7 +1229,7 @@ void *sys_mmap2(void *addr, size_t length, int prot,
         rc = (sysret_t)lwp_mmap2(lwp_self(), addr, length, prot, flags, fd, pgoffset);
     }
 
-    return (char *)rc + offset;
+    return rc < 0 ? (char *)rc : (char *)rc + offset;
 }
 
 sysret_t sys_munmap(void *addr, size_t length)