arc: Add new GAS tests for ARCv3.

Add new assembler tests for ARCv3 ISA. All the new tests are added in
a distinct folder named arc64.

gas/
xxxx-xx-xx  Claudiu Zissulescu <claziss@synopsys.com>

	* gas/testsuite/gas/arc64/arc64.exp: New file.
	* gas/testsuite/gas/arc64/float01.d: Likewise.
	* gas/testsuite/gas/arc64/float01.s: Likewise.
	* gas/testsuite/gas/arc64/ldd.d: Likewise.
	* gas/testsuite/gas/arc64/ldd.s: Likewise.
	* gas/testsuite/gas/arc64/lddl.d: Likewise.
	* gas/testsuite/gas/arc64/lddl.s: Likewise.
	* gas/testsuite/gas/arc64/load.d: Likewise.
	* gas/testsuite/gas/arc64/load.s: Likewise.
	* gas/testsuite/gas/arc64/st.d: Likewise.
	* gas/testsuite/gas/arc64/st.s: Likewise.
	* gas/testsuite/gas/arc64/std.d: Likewise.
	* gas/testsuite/gas/arc64/std.s: Likewise.
	* gas/testsuite/gas/arc64/stdl.d: Likewise.
	* gas/testsuite/gas/arc64/stdl.s: Likewise.
	* gas/testsuite/gas/arc64/stl.d: Likewise.
	* gas/testsuite/gas/arc64/stl.s: Likewise.

Signed-off-by: Claudiu Zissulescu <claziss@synopsys.com>