Sort filename (if given) by name for consistent output

Currently the generation of lamdas can change depending on when the
source file is processed.

This sorts the array of files (if given) to always have a predictable
order independent of order given on the commandline / arguments.

Relates to #1921

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/batch/Main.java

@@ -1747,6 +1747,10 @@ public boolean compile(String[] argv) {
 	// decode command line arguments
 	try {
 		configure(argv);
+		if (this.filenames != null) {
+			// sort file names so we have a consistent order of compiling / handling them
+			Arrays.sort(this.filenames);
+		}
 		if (this.progress != null)
 			this.progress.begin(this.filenames == null ? 0 : this.filenames.length * this.maxRepetition);
 		if (this.proceed) {