Fix fd_handlers when using recursive main loops.

Fix fd_handlers when using recursive main loops.

If an fd_handler created a recursive main loop (just called
ecore_main_loop_begin()), then this recursive main loop should
continue to process fd_handlers from there and on, thus
fd_handler_current (and win32_handler_current) was added. When going
back from recursion, the current iterator should be updated properly.

This patch also fixes the deletion of fd_handler from recursive main
loops by reference counting them. This way, the node will not be
free()d inside inner loop cleanups and then crash when going back to
outer loop.

PS: win32 code is untested (or even compiled).

The following test case used to crash but not anymore:

#include <Ecore.h>
#include <Eina.h>
#include <unistd.h>

static int _log_dom;
#define INF(...) EINA_LOG_DOM_INFO(_log_dom, __VA_ARGS__)
#define ERR(...) EINA_LOG_DOM_ERR(_log_dom, __VA_ARGS__)

static Ecore_Fd_Handler *handle;
static int a[2], b[2];

static int cb2(void *data, Ecore_Fd_Handler *h)
{
    INF("cb2 - delete cb1 handle");
    ecore_main_fd_handler_del(handle);
    ecore_main_loop_quit(); /* quits inner main loop */
    return 0;
}

static int cb1(void *data, Ecore_Fd_Handler *h)
{
    unsigned char ch = 222;

    INF("cb1: begin");
    INF("    add cb2");
    ecore_main_fd_handler_add(b[0], ECORE_FD_READ, cb2, NULL, NULL, NULL);
    INF("    wake up pipe b");
    if (write(b[1], &ch, 1) != 1)
        ERR("could not write to pipe b");
    INF("    inner main loop begin (recurse)");
    ecore_main_loop_begin(); /* will it crash due
                              * ecore_main_fd_handler_del(handle)
                              * inside cb2()? It used to!
                              */
    INF("cb1: end");

    ecore_main_loop_quit(); /* quits outer main loop */

    return 0;
}

int main(void)
{
    unsigned char ch = 111;

    ecore_init();

    _log_dom = eina_log_domain_register("test", EINA_COLOR_CYAN);
    pipe(a);
    pipe(b);

    /*
     * Creating a new main loop from inside an fd_handler callback,
     * and inside this new (inner) main loop deleting the caller
     * callback used to crash since the handle would be effectively
     * free()d, but when the recursion is over the pointer would be
     * used.
     */

    INF("main: begin");
    handle = ecore_main_fd_handler_add
        (a[0], ECORE_FD_READ, cb1, NULL, NULL, NULL);
    INF("main: wake up pipe a");
    if (write(a[1], &ch, 1) != 1)
        ERR("could not write to pipe a");
    ecore_main_loop_begin();
    INF("main: end");
    return 0;
}

git-svn-id: http://svn.enlightenment.org/svn/e/trunk/ecore@46443 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33