PR 33229 nds32 gas segfaults on gcc output

PR 33229 nds32 gas segfaults on gcc output

Commit 1ac26e9f7ac2 replaced ISSPACE with is_whitespace, but the
former returns true on EOL while the latter does not.  Sprinkle
is_end_of_stmt tests to fix this bug.

The same segfault can be triggered by a ".relax_hint" with no
following instructions.  Fix that too.

	* config/tc-nds32.c (nds32_lookup_pseudo_opcode): Use
	is_end_of_stmt along with is_whitespace.
	(nds32_relax_relocs, nds32_relax_hint, nds32_flag),
	(ict_model: Likewise.
	(nds32_elf_append_relax_relocs): Return on no opcode.
	* testsuite/gas/nds32/nds32.exp: Find .d files automatically.
	* testsuite/gas/nds32/pr33229.d,
	* testsuite/gas/nds32/pr33229.s: New test.