core: Don't allow free to mean ast_free (and malloc, etc..).

This gets rid of most old libc free/malloc/realloc and replaces them
with ast_free and friends. When compiling with MALLOC_DEBUG you'll
notice it when you're mistakenly using one of the libc variants. For
the legacy cases you can define WRAP_LIBC_MALLOC before including
asterisk.h.

Even better would be if the errors were also enabled when compiling
without MALLOC_DEBUG, but that's a slightly more invasive header
file change.

Those compiling addons/format_mp3 will need to rerun
./contrib/scripts/get_mp3_source.sh.

ASTERISK-24348 #related
Review: https://reviewboard.asterisk.org/r/4015/


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@423978 f38db490-d61c-443f-a65b-d21fe96a405b