When the offending code is reached, new_crr is either uninitalized or
have been set to NULL. This patch removes the following warning:

beam/erl_alloc_util.c:3510:6: warning: variable 'new_crr' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
        if (!(flags & CFLG_FORCE_MSEG)) {
            ^~~~~~~~~~~~~~~~~~~~~~~~~~
beam/erl_alloc_util.c:3567:23: note: uninitialized use occurs here
        DEBUG_SAVE_ALIGNMENT(new_crr);
                             ^~~~~~~
beam/erl_alloc_util.c:674:51: note: expanded from macro 'DEBUG_SAVE_ALIGNMENT'
    UWord algnmnt__ = sizeof(Unit_t) - (((UWord) (C)) % sizeof(Unit_t));\
                                                  ^
beam/erl_alloc_util.c:3510:2: note: remove the 'if' if its condition is always true
        if (!(flags & CFLG_FORCE_MSEG)) {
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
beam/erl_alloc_util.c:3438:23: note: initialize the variable 'new_crr' to silence this warning
    Carrier_t *new_crr, *old_crr;
                      ^
                       = NULL

* lukas/erts/supercarrier_fix/OTP-11149:
  Improve error info when main carrier creation fails

Conflicts:
	erts/emulator/test/alloc_SUITE.erl

* sverk/allctr-4byte-align-bug:
  erts: Fix alignment bug in allocator start code

OTP-11496

Also fix testcase that failed due to main carrier creation failure.

* rickard/acul-bug/OTP-11456:
  Ensure carrier pool only accessed by schedulers

Bug never released.

The switch "+Musac <boolean>" controls if sys_alloc carriers
are allowed.

Disable carrier pool for the thread safe allocator instance 0.
This since non-managed threads allocates and deallocates memory
in this instance, and only managed threads are allowed to
access the carrier pool.

* Coalescing and trimming of free segments in supercarrier
* Management of super aligned and super unaligned areas in
  supercarrier
* Management of reservation of physical memory
* erts_mseg usage of erts_mmap

Introduce unconditional ERTS_ASSERT
and use that for both ASSERT and ASSERT_EXPR.