Compile as C17 code

[akurtakov]

GCC 15 defaults to C23 standard but it's not feasible to use it as even Xlib.h is not compatible yet e.g.

/usr/include/X11/Xlib.h:2105:5: note: expected ‘int (*)(Display *,
XEvent *, char *)’ but argument is of type ‘int (*)(void)’
 2105 |     Bool (*) (

Fixes #1865 .

[github-actions]

Test Results

   539 files   -  6     539 suites   - 6   34m 10s ⏱️ + 4m 30s
 4 330 tests  - 37   4 316 ✅  - 35   13 💤  - 3  1 ❌ +1 
16 579 runs   - 37  16 467 ✅  - 35  111 💤  - 3  1 ❌ +1 

For more details on these failures, see this check.

Results for commit 41ab709. ± Comparison against base commit e4fc88a.

This pull request removes 37 tests.

AllWin32Tests org.eclipse.swt.graphics.ImageWin32Tests ‑ testImageDataForDifferentFractionalZoomsShouldBeDifferent
AllWin32Tests org.eclipse.swt.graphics.ImageWin32Tests ‑ testImageShouldHaveDimesionAsPerZoomLevel
AllWin32Tests org.eclipse.swt.tests.win32.Test_org_eclipse_swt_dnd_DND ‑ testByteArrayTransfer
AllWin32Tests org.eclipse.swt.tests.win32.Test_org_eclipse_swt_dnd_DND ‑ testFileTransfer
AllWin32Tests org.eclipse.swt.tests.win32.Test_org_eclipse_swt_dnd_DND ‑ testHtmlTransfer
AllWin32Tests org.eclipse.swt.tests.win32.Test_org_eclipse_swt_dnd_DND ‑ testImageTransfer_fromCopiedImage
AllWin32Tests org.eclipse.swt.tests.win32.Test_org_eclipse_swt_dnd_DND ‑ testImageTransfer_fromImage
AllWin32Tests org.eclipse.swt.tests.win32.Test_org_eclipse_swt_dnd_DND ‑ testImageTransfer_fromImageData
AllWin32Tests org.eclipse.swt.tests.win32.Test_org_eclipse_swt_dnd_DND ‑ testImageTransfer_fromImageDataFromImage
AllWin32Tests org.eclipse.swt.tests.win32.Test_org_eclipse_swt_dnd_DND ‑ testRtfTransfer
…

[akurtakov]

Jenkins is fine. Windows problem is unrelated to Linux change. Merging.

[akurtakov]

@HeikoKlare What is the plan for this long standing Windows test problem?