Prefer signed integer types in module code

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.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/lread.c b/src/lread.c
index f7ce0daf1fa..43100d9f699 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -979,8 +979,8 @@ This uses the variables `load-suffixes' and `load-file-rep-suffixes'.  */)
 static bool
 suffix_p (Lisp_Object string, const char *suffix)
 {
-  size_t suffix_len = strlen (suffix);
-  size_t string_len = SBYTES (string);
+  ptrdiff_t suffix_len = strlen (suffix);
+  ptrdiff_t string_len = SBYTES (string);
 
   return string_len >= suffix_len && !strcmp (SSDATA (string) + string_len - suffix_len, suffix);
 }