*.[ch]: manually align parameter lists

In previous patches, extern was mechanically removed from function
declarations without care to formatting, causing parameter lists to be
misaligned. Manually format changed sections such that the parameter
lists should be realigned.

Viewing this patch with 'git diff -w' should produce no output.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

xdiff-interface.h

@@ -47,7 +47,7 @@ void discard_hunk_line(void *priv,
  * are treated for the comparision.
  */
 int xdiff_compare_lines(const char *l1, long s1,
-			       const char *l2, long s2, long flags);
+			const char *l2, long s2, long flags);
 
 /*
  * Returns a hash of the string s of length len.