Merge branch 'js/mingw-no-nedmalloc'

Stop using unmaintained custom allocator in Windows build which was
the last user of the code.

* js/mingw-no-nedmalloc:
  mingw: remove the vendored compat/nedmalloc/ subtree
  mingw: drop the build-system plumbing for nedmalloc
  mingw: stop using nedmalloc

diff --cc Makefile
Simple merge

diff --cc config.mak.uname
Simple merge

diff --cc meson.build
Simple merge