* modules/mod-test/mod-test.c (Fmod_test_return_t)
(Fmod_test_sum, Fmod_test_signal, Fmod_test_throw)
(Fmod_test_non_local_exit_funcall, Fmod_test_globref_make)
(Fmod_test_string_a_to_b, Fmod_test_userptr_make)
(Fmod_test_userptr_get, Fmod_test_vector_fill)
(Fmod_test_vector_eq): Arg counts are ptrdiff_t, not int.
(finalizer): Remove; no longer used.

* modules/mod-test/mod-test.c: Include stdlib.h, to avoid warnings
about missing prototype of malloc.
* modules/mod-test/Makefile (CFLAGS): Add -std=gnu99, to avoid
compiler warnings.

Generally speaking, at the C level the Emacs source code prefers
signed types like ‘ptrdiff_t’ to unsigned types like ‘size_t’,
partly to avoid the usual signedness confusion when comparing values.
Change the module API to follow this convention.
Use ‘int’ for small values that can’t exceed INT_MAX.
* modules/mod-test/mod-test.c (Fmod_test_globref_make)
(Fmod_test_string_a_to_b, Fmod_test_vector_fill)
(Fmod_test_vector_eq):
* src/emacs-module.c (struct emacs_value_frame)
(module_make_global_ref, module_free_global_ref)
(module_copy_string_contents, module_make_string)
(module_vec_set, module_vec_get, module_vec_size):
* src/emacs-module.h (struct emacs_runtime, struct emacs_env_25):
* src/lread.c (suffix_p):
Prefer signed to unsigned integer types.

Remove ‘const’ qualifier from locals that were newly added.
We don’t normally bother declaring locals with ‘const’ even
though they are not modified, for the same reason we don’t
bother declaring them with ‘register’ even though their
addresses are not taken; the advantage in compile-time
checking isn’t worth the loss of readability.
* modules/mod-test/mod-test.c (Fmod_test_non_local_exit_funcall)
(Fmod_test_vector_fill, Fmod_test_vector_eq):
* src/emacs-module.c (MODULE_SETJMP_1)
(module_make_global_ref, module_free_global_ref)
(module_non_local_exit_get, module_make_function)
(module_extract_integer, module_extract_float)
(module_get_user_ptr, module_set_user_ptr)
(module_get_user_finalizer, module_set_user_finalizer)
(module_vec_get, Fmodule_call)
(module_non_local_exit_signal_1)
(module_non_local_exit_throw_1, lisp_to_value)
(finalize_storage, allocate_emacs_value, mark_modules)
(module_handle_signal, module_handle_throw)
(module_format_fun_env):
* src/eval.c (push_handler, push_handler_nosignal)
(init_handler):
* src/lread.c (suffix_p):
Omit unnecessary ‘const’.

* modules/mod-test/mod-test.c (sum, Fmod_test_sum):
* src/emacs-module.c (module_extract_integer)
(module_make_integer):
* src/emacs-module.h (struct emacs_env_25):
Prefer intmax_t to int64_t.  This doesn’t change the generated
code on any of the machines Emacs currently ports to, but it’s
at least in theory more future-proof as C99 doesn’t guarantee
that int64_t exists.

* src/emacs-module.c: Rename from src/module.c.
* src/emacs-module.h: Rename from src/module.h.
All uses changed.

This is mostly indenting and spacing changes.  Also, remove
some unnecessary static decls instead of bothering to reindent them.
* src/module.h (EMACS_EXTERN_C_BEGIN): Remove, and do this inline,
as most other Emacs files do for this sort of thing.

* modules/mod-test/Makefile (EMACS, SO): New variables.
(CFLAGS): When SO = dll, don't use -fPIC.
(check): New target, runs the test.

* .gitignore: Add former contents of modules/.gitignore.
* modules/.gitignore: Remove.

Put them in the usual format for GNU Emacs copyright notices.