Fix some tests in --without-all builds

* test/lisp/image-tests.el (image-type/from-filename):
* test/src/image-tests.el (image-tests-init-image-library):
* test/src/thread-tests.el (threads-test-bug33073): Fix tests in
--without-all builds.

test/lisp/image-tests.el

@@ -82,7 +82,8 @@
 (ert-deftest image-type/from-filename ()
   ;; On emba, `image-types' and `image-load-path' do not exist.
   (skip-unless (and (bound-and-true-p image-types)
-                    (bound-and-true-p image-load-path)))
+                    (bound-and-true-p image-load-path)
+                    (image-type-available-p 'jpeg)))
   (should (eq (image-type "foo.jpg") 'jpeg)))
 
 (defun image-tests--type-from-file-header (type)

test/src/image-tests.el

@@ -239,7 +239,6 @@
 (ert-deftest image-tests-init-image-library ()
   (skip-unless (fboundp 'init-image-library))
   (should (init-image-library 'pbm)) ; built-in
-  (should (init-image-library 'xpm)) ; built-in
   (should-not (init-image-library 'invalid-image-type)))
 
 ;;; image-tests.el ends here

test/src/thread-tests.el

@@ -389,6 +389,7 @@
     (should (equal (thread-last-error) '(error "Die, die, die!")))))
 
 (ert-deftest threads-test-bug33073 ()
+  (skip-unless (fboundp 'make-thread))
   (let ((th (make-thread 'ignore)))
     (should-not (equal th main-thread))))