Better handling for the random pi4 errors

[nedtwigg]

SWT doesn't ship pi4 as of Eclipse 4.21 or 4.20

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk/OS.java

Lines 83 to 97 in 3716c61

	String propertyName = "SWT_GTK4";
	String gtk4 = getEnvironmentalVariable(propertyName);
	if (gtk4 != null && gtk4.equals("1")) {
	try {
	Library.loadLibrary("swt-pi4");
	} catch (Throwable e) {
	Library.loadLibrary("swt-pi3");
	}
	} else {
	try {
	Library.loadLibrary("swt-pi3");
	} catch (Throwable e) {
	Library.loadLibrary("swt-pi4");
	}
	}

The pi4 thing was introduced Nov 2018, so maybe 4.10 (released Dec 2018).

db2d0d1