Revert "Prepend hostname to subsection used to store file timestamp resolution"

This reverts commit e102bbed99.

Resolving the hostname comes with a performance penalty. We no longer
store the timestamp resolution in the global git config which might be
copied around to other machines but in a dedicated jgit config meant for
automatically determined options like timestamp resolution. Hence there
is no strong reason anymore to have a hardware specific identifier in
the subsection name of file timestamp resolution options.

Bug: 560414
Change-Id: If8dcabe981eb1792db84643850faa6033f14b1cf
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/util/FS.java

@@ -246,9 +246,8 @@ public abstract class FS {
 			background.set(async);
 		}
 
-		private static final String javaVersionPrefix = SystemReader
-				.getInstance().getHostname() + '|'
-				+ System.getProperty("java.vendor") + '|' //$NON-NLS-1$
+		private static final String javaVersionPrefix = System
+				.getProperty("java.vendor") + '|' //$NON-NLS-1$
 				+ System.getProperty("java.version") + '|'; //$NON-NLS-1$
 
 		private static final Duration FALLBACK_MIN_RACY_INTERVAL = Duration