Use add/sub/neg insns to eliminate compare/test insns on H8

Use add/sub/neg insns to eliminate compare/test insns on H8

gcc/

	* config/h8300/addsub.md (addqi3_clobber_flags): Rename to
	addqi3_flags and annotate with a <cczn> for define_subst.
	(addhi3_h8sx_clobber_flags): Likewise.
	(subqi3_clobber_flags, sub<mode>3_clobber_flags): Likewise.
	(neg<mode2>_clobber_flags): Similarly.
	(addsi3_clobber_flags): Similarly.  Update last argument to
	output_plussi to distinguish when we need flags or do not need
	flags.
	(addhi3_clobber_flags): Similarly.  Twiddle code for cases
	+-1, +-2 and +-4.
	* config/h8300/h8300.md: Define iterators, mode attributes and
	substitutions for use in compare/test elimination.
	* config/h8300/jumpcall.md (branch, branch_1): Use H8cc mode
	iterator to cover the different modes for the CC register.
	(branch_1_false): Likewise.

gcc/testsuite
	* gcc.target/h8300/add.c: New test.
	* gcc.target/h8300/add-2.c: New test.
	* gcc.target/h8300/add-3.c: New test.
	* gcc.target/h8300/sub.c: New test.
	* gcc.target/h8300/sub-2.c: New test.
	* gcc.target/h8300/sub-3.c: New test.