gtk+3: disable wayland without opengl

Wayland backend requires epoxy so it will pull in a requirement for opengl
While doing some tests in building old stuff like matchbox-terminal with
vte 0.76, I encountered an issue with building matchbox-terminal without
opengl in DISTRO_FEATURES.

Explicitly stating that the Wayland backend requires opengl fixes this problem
and allows matchbox-terminal to be used without.
---
 meta/recipes-gnome/gtk+/gtk+3.inc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Thank you for your submission. Patchtest identified one
or more issues with the patch. Please see the log below for
more information:

---
Testing patch /home/patchtest/share/mboxes/gtk-3-disable-wayland-without-opengl.patch

FAIL: test Signed-off-by presence: Mbox is missing Signed-off-by. Add it manually or with "git commit --amend -s" (test_mbox.TestMbox.test_signed_off_by_presence)

PASS: test author valid (test_mbox.TestMbox.test_author_valid)
PASS: test commit message presence (test_mbox.TestMbox.test_commit_message_presence)
PASS: test max line length (test_metadata.TestMetadata.test_max_line_length)
PASS: test mbox format (test_mbox.TestMbox.test_mbox_format)
PASS: test non-AUH upgrade (test_mbox.TestMbox.test_non_auh_upgrade)
PASS: test shortlog format (test_mbox.TestMbox.test_shortlog_format)
PASS: test shortlog length (test_mbox.TestMbox.test_shortlog_length)

SKIP: pretest pylint: No python related patches, skipping test (test_python_pylint.PyLint.pretest_pylint)
SKIP: pretest src uri left files: No modified recipes, skipping pretest (test_metadata.TestMetadata.pretest_src_uri_left_files)
SKIP: test CVE check ignore: No modified recipes or older target branch, skipping test (test_metadata.TestMetadata.test_cve_check_ignore)
SKIP: test CVE tag format: No new CVE patches introduced (test_patch.TestPatch.test_cve_tag_format)
SKIP: test Signed-off-by presence: No new CVE patches introduced (test_patch.TestPatch.test_signed_off_by_presence)
SKIP: test Upstream-Status presence: No new CVE patches introduced (test_patch.TestPatch.test_upstream_status_presence_format)
SKIP: test bugzilla entry format: No bug ID found (test_mbox.TestMbox.test_bugzilla_entry_format)
SKIP: test lic files chksum modified not mentioned: No modified recipes, skipping test (test_metadata.TestMetadata.test_lic_files_chksum_modified_not_mentioned)
SKIP: test lic files chksum presence: No added recipes, skipping test (test_metadata.TestMetadata.test_lic_files_chksum_presence)
SKIP: test license presence: No added recipes, skipping test (test_metadata.TestMetadata.test_license_presence)
SKIP: test pylint: No python related patches, skipping test (test_python_pylint.PyLint.test_pylint)
SKIP: test series merge on head: Merge test is disabled for now (test_mbox.TestMbox.test_series_merge_on_head)
SKIP: test src uri left files: No modified recipes, skipping pretest (test_metadata.TestMetadata.test_src_uri_left_files)
SKIP: test summary presence: No added recipes, skipping test (test_metadata.TestMetadata.test_summary_presence)
SKIP: test target mailing list: Series merged, no reason to check other mailing lists (test_mbox.TestMbox.test_target_mailing_list)

---

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