MINOR: haproxy: Make use of deinit_and_exit() for clean exits

MINOR: haproxy: Make use of deinit_and_exit() for clean exits

Particularly cleanly deinit() after a configuration check to clean up the
output of valgrind which reports "possible losses" without a deinit() and
does not with a deinit(), converting actual losses into proper hard losses
which makes the whole stuff easier to analyze.

As an example, given an example configuration of the following:

    frontend foo
    	bind *:8080
    	mode http

Running `haproxy -c -f cfg` within valgrind will report 4 possible losses:

    $ valgrind --leak-check=full ./haproxy -c -f ./example.cfg
    ==21219== Memcheck, a memory error detector
    ==21219== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
    ==21219== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
    ==21219== Command: ./haproxy -c -f ./example.cfg
    ==21219==
    [WARNING] 165/001100 (21219) : config : missing timeouts for frontend 'foo'.
       | While not properly invalid, you will certainly encounter various problems
       | with such a configuration. To fix this, please ensure that all following
       | timeouts are set to a non-zero value: 'client', 'connect', 'server'.
    Warnings were found.
    Configuration file is valid
    ==21219==
    ==21219== HEAP SUMMARY:
    ==21219==     in use at exit: 1,436,631 bytes in 130 blocks
    ==21219==   total heap usage: 153 allocs, 23 frees, 1,447,758 bytes allocated
    ==21219==
    ==21219== 7 bytes in 1 blocks are possibly lost in loss record 5 of 54
    ==21219==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==21219==    by 0x5726489: strdup (strdup.c:42)
    ==21219==    by 0x468FD9: bind_conf_alloc (listener.h:158)
    ==21219==    by 0x468FD9: cfg_parse_listen (cfgparse-listen.c:557)
    ==21219==    by 0x459DF3: readcfgfile (cfgparse.c:2167)
    ==21219==    by 0x5056CD: init (haproxy.c:2021)
    ==21219==    by 0x418232: main (haproxy.c:3121)
    ==21219==
    ==21219== 14 bytes in 1 blocks are possibly lost in loss record 9 of 54
    ==21219==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==21219==    by 0x5726489: strdup (strdup.c:42)
    ==21219==    by 0x468F9B: bind_conf_alloc (listener.h:154)
    ==21219==    by 0x468F9B: cfg_parse_listen (cfgparse-listen.c:557)
    ==21219==    by 0x459DF3: readcfgfile (cfgparse.c:2167)
    ==21219==    by 0x5056CD: init (haproxy.c:2021)
    ==21219==    by 0x418232: main (haproxy.c:3121)
    ==21219==
    ==21219== 128 bytes in 1 blocks are possibly lost in loss record 35 of 54
    ==21219==    at 0x4C2FB55: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==21219==    by 0x468F90: bind_conf_alloc (listener.h:152)
    ==21219==    by 0x468F90: cfg_parse_listen (cfgparse-listen.c:557)
    ==21219==    by 0x459DF3: readcfgfile (cfgparse.c:2167)
    ==21219==    by 0x5056CD: init (haproxy.c:2021)
    ==21219==    by 0x418232: main (haproxy.c:3121)
    ==21219==
    ==21219== 608 bytes in 1 blocks are possibly lost in loss record 46 of 54
    ==21219==    at 0x4C2FB55: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==21219==    by 0x4B953A: create_listeners (listener.c:576)
    ==21219==    by 0x4578F6: str2listener (cfgparse.c:192)
    ==21219==    by 0x469039: cfg_parse_listen (cfgparse-listen.c:568)
    ==21219==    by 0x459DF3: readcfgfile (cfgparse.c:2167)
    ==21219==    by 0x5056CD: init (haproxy.c:2021)
    ==21219==    by 0x418232: main (haproxy.c:3121)
    ==21219==
    ==21219== LEAK SUMMARY:
    ==21219==    definitely lost: 0 bytes in 0 blocks
    ==21219==    indirectly lost: 0 bytes in 0 blocks
    ==21219==      possibly lost: 757 bytes in 4 blocks
    ==21219==    still reachable: 1,435,874 bytes in 126 blocks
    ==21219==         suppressed: 0 bytes in 0 blocks
    ==21219== Reachable blocks (those to which a pointer was found) are not shown.
    ==21219== To see them, rerun with: --leak-check=full --show-leak-kinds=all
    ==21219==
    ==21219== For counts of detected and suppressed errors, rerun with: -v
    ==21219== ERROR SUMMARY: 4 errors from 4 contexts (suppressed: 0 from 0)

Re-running the same command with the patch applied will not report any
losses any more:

    $ valgrind --leak-check=full ./haproxy -c -f ./example.cfg
    ==22124== Memcheck, a memory error detector
    ==22124== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
    ==22124== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
    ==22124== Command: ./haproxy -c -f ./example.cfg
    ==22124==
    [WARNING] 165/001503 (22124) : config : missing timeouts for frontend 'foo'.
       | While not properly invalid, you will certainly encounter various problems
       | with such a configuration. To fix this, please ensure that all following
       | timeouts are set to a non-zero value: 'client', 'connect', 'server'.
    Warnings were found.
    Configuration file is valid
    ==22124==
    ==22124== HEAP SUMMARY:
    ==22124==     in use at exit: 313,864 bytes in 82 blocks
    ==22124==   total heap usage: 153 allocs, 71 frees, 1,447,758 bytes allocated
    ==22124==
    ==22124== LEAK SUMMARY:
    ==22124==    definitely lost: 0 bytes in 0 blocks
    ==22124==    indirectly lost: 0 bytes in 0 blocks
    ==22124==      possibly lost: 0 bytes in 0 blocks
    ==22124==    still reachable: 313,864 bytes in 82 blocks
    ==22124==         suppressed: 0 bytes in 0 blocks
    ==22124== Reachable blocks (those to which a pointer was found) are not shown.
    ==22124== To see them, rerun with: --leak-check=full --show-leak-kinds=all
    ==22124==
    ==22124== For counts of detected and suppressed errors, rerun with: -v
    ==22124== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

It might be worth investigating what exactly HAProxy does to lose pointers
to the start of those 4 memory areas and then to be able to still free them
during deinit(). If HAProxy is able to free them, they ideally should be
"still reachable" and not "possibly lost".