bug#20736: several build failures with new map functions

[Paul Eggert]

"make check" fails with the new map functions, in several different ways. 
Nicholas, can you please fix these?  Thanks.

  ELC      emacs-lisp/map.elc

In map-merge:
emacs-lisp/map.el:242:31:Warning: reference to free variable `m'

In map--dispatch:
emacs-lisp/map.el:257:11:Warning: macro `map--dispatch' defined too late

In map--delete-array:
emacs-lisp/map.el:341:16:Warning: reference to free variable `m'

In end of data:
emacs-lisp/map.el:372:1:Warning: the function `m' is not known to be defined.

...

Compiling map-tests.el

In toplevel form:
map-tests.el:91:15:Warning: variable reference to nonvariable `[1 2 3]'
map-tests.el:91:15:Error: Wrong type argument: symbolp, [1 2 3]
Makefile:64: recipe for target 'map-tests.elc' failed
make[3]: *** [map-tests.elc] Error 1