S/390: Fix missing .size directives.

S/390: Fix missing .size directives.

It seems at some point the .size hook was hijacked to emit some
machine-specific directives, and the actual .size directive was
forgotten.  This caused problems for split-stack support, since
linker couldn't scan the function body for non-split-stack calls.

gcc/ChangeLog:

	* config/s390/s390.c (s390_asm_declare_function_size): Add code
	to actually emit the .size directive.

From-SVN: r232669