chore: silence build warnings on non-macOS toolchains

- ekp_hyphen.c: check fgets return when skipping the dictionary
  encoding line (gcc -Wunused-result via glibc fortify); behavior
  unchanged — an empty file already fell through to EOF in the loops
- ekp-utils.el: declare-function for font-info, which does not exist
  in non-window-system builds (emacs-nox); call site is runtime-guarded
  by display-multi-font-p. Keeps byte-compile-error-on-warn green.

Verified: clean gcc build + 36/36 ERT + 300-case fuzz on Ubuntu 24.04
(Emacs 29.3, arm64), clean clang build + 36/36 ERT on macOS (30.2).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ekp-utils.el

@@ -41,6 +41,10 @@ information is available (batch mode, tty frames)."
     (let ((family (face-attribute 'default :family)))
       (if (stringp family) family (format "%s" family)))))
 
+;; GUI-only C function; absent in non-window-system builds (emacs-nox).
+;; Call sites are guarded by `display-multi-font-p'.
+(declare-function font-info "font.c" (name &optional frame))
+
 (defun ekp-font-monospace-p (font-family)
   "Return non-nil if FONT-FAMILY appears to be monospace.
 Returns nil (unknown) when font information is unavailable."

ekp_c/ekp_hyphen.c

@@ -99,7 +99,9 @@ ekp_hyphenator_t *ekp_hyphen_create(const char *dict_path)
     char line[256];
     size_t count = 0;
 
-    fgets(line, sizeof(line), fp);  /* skip encoding line */
+    if (!fgets(line, sizeof(line), fp)) {
+        /* empty file: no encoding line to skip; count loop sees EOF */
+    }
 
     while (fgets(line, sizeof(line), fp)) {
         size_t len = strlen(line);
@@ -128,7 +130,9 @@ ekp_hyphenator_t *ekp_hyphen_create(const char *dict_path)
 
     /* Second pass: parse patterns */
     rewind(fp);
-    fgets(line, sizeof(line), fp);  /* skip encoding line */
+    if (!fgets(line, sizeof(line), fp)) {
+        /* empty file: no encoding line to skip; parse loop sees EOF */
+    }
 
     size_t idx = 0;
     while (fgets(line, sizeof(line), fp)) {