stdlib: Add common bsd mkstemps function

Change-Id: I8c54f4b42e8b41f9a769b8b53f074a307b1a054c

libroot: mktemp.c: fix gcc5 warnings.

libroot: mktemp.c: use rand_r() and set seed only on first call
This avoid to break caller's own srand() and having the same seed
if called twice very quickly.
Thanks david.given for a better fix for #13660.

libroot: make mktemp() more random
... by seeding rand() with process id, user id and current time.
This fix #13660

Introduce __set_errno() throughout libroot.

* add errno_private.h, which defines the __set_errno() macro with
and without tracing
* instead of setting errno manually, all libroot's code now invokes
__set_errno(), which makes it much easier to trace changes to errno
* redirect glibc's use of __set_errno() to our own version

* Uncommenting POSIX mkdtemp function. Tested.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@28840 a95241bf-73f2-0310-859d-f6bbb57e9c96

Renamed src/kernel to src/system.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12359 a95241bf-73f2-0310-859d-f6bbb57e9c96

Introduce __set_errno() throughout libroot.

* add errno_private.h, which defines the __set_errno() macro with
and without tracing
* instead of setting errno manually, all libroot's code now invokes
__set_errno(), which makes it much easier to trace changes to errno
* redirect glibc's use of __set_errno() to our own version

* Uncommenting POSIX mkdtemp function. Tested.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@28840 a95241bf-73f2-0310-859d-f6bbb57e9c96

Renamed src/kernel to src/system.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12359 a95241bf-73f2-0310-859d-f6bbb57e9c96