Fixes to allow diffutils to build with gcc v6.

RP
2016/5/25

Index: diffutils-2.8.1/lib/posix/regex.h
===================================================================
--- diffutils-2.8.1.orig/lib/posix/regex.h
+++ diffutils-2.8.1/lib/posix/regex.h
@@ -529,7 +529,9 @@ extern int re_exec _RE_ARGS ((const char
 /* For now unconditionally define __restrict_arr to expand to nothing.
    Ideally we would have a test for the compiler which allows defining
    it to restrict.  */
+#ifndef __restrict_arr
 #define __restrict_arr
+#endif
 
 /* POSIX compatibility.  */
 extern int regcomp _RE_ARGS ((regex_t *__restrict __preg,
Index: diffutils-2.8.1/src/diff.c
===================================================================
--- diffutils-2.8.1.orig/src/diff.c
+++ diffutils-2.8.1/src/diff.c
@@ -71,6 +71,7 @@ static void usage (void);
 static bool recursive;
 
 /* In context diffs, show previous lines that match these regexps.  */
+struct re_pattern_buffer function_regexp;
 static struct regexp_list function_regexp_list;
 
 /* Ignore changes affecting only lines that match these regexps.  */