Revert "Remove __builtin_arc_aligned because it is redundant with __alignof__."

rationale: __alignof__ doesn't do the right thing for our purposes when
taking a pointer, casting it to and fro, and dereferencing it as a char.

This reverts commit 8cb30724c7d7070a9a895cd44a0bdcd5faf21803.

Conflicts:
	gcc/ChangeLog.ARC
2013-08-31  Joern Rennecke  <joern.rennecke@embecosm.com>

        * config/arc/arc.c (arc_expand_builtin): Remove obsolete code.
        Only apply INTVAL to CONST_INT.
        Fix alignment calculation for constants.
        Unify requirements for value of requested alignment.
        Add type-based alignment check.
        Don't bother copying the return value, just return it.
        * doc/extend.texi (__builtin_arc_aligned): Refine description.

2013-08-31  Joern Rennecke  <joern.rennecke@embecosm.com>
            Vineet Gupta  <Vineet.Gupta@synopsys.com>

        * testsuite/gcc.target/arc/builtin_arc_aligned-1.c: New test.
        * testsuite/gcc.target/arc/builtin_arc_aligned-2.c: Likewise.
        * testsuite/gcc.target/arc/builtin_arc_aligned-3.c: Likewise.
ChangeLog whitespace fix.