S390 gdbserver: Mark local funcs/vars as static

S390 gdbserver: Mark local funcs/vars as static

Compiling with '-Wmissing-declarations' yields warnings in
linux-s390-low.c.  To fix this, mark appropriate functions as static.

gdb/gdbserver/ChangeLog:

	* linux-s390-low.c (s390_emit_eq_goto): Mark function static.
	(s390_emit_ne_goto): Likewise.
	(s390_emit_lt_goto): Likewise.
	(s390_emit_le_goto): Likewise.
	(s390_emit_gt_goto): Likewise.
	(s390_emit_ge_goto): Likewise.
	(s390x_emit_eq_goto): Likewise.
	(s390x_emit_ne_goto): Likewise.
	(s390x_emit_lt_goto): Likewise.
	(s390x_emit_le_goto): Likewise.
	(s390x_emit_gt_goto): Likewise.
	(s390x_emit_ge_goto): Likewise.
	(s390_emit_ops_impl): Mark variable static.
	(s390x_emit_ops): Likewise.