varasm.c broken by recent patch

[John Carr]

This patch broke varasm.c for RS/6000:

	* varasm.c (assemble_string): Remove unused variable 'i'. 
	(immed_double_const): Remove unused variable 'in_current_obstack'. 
	(immed_real_const_1): Likewise.
	(output_constant_pool): Remove unreferenced label 'done'.
	(output_constant): Remove unused variable 'x'.

The label "done" is used by the ASM_OUTPUT_SPECIAL_POOL_ENTRY macro and
must be restored.