params: Fix up help.exp testing

params: Fix up help.exp testing

This patch fixes:
Running /usr/src/gcc/gcc/testsuite/gcc.misc-tests/help.exp ...
FAIL: compiler driver --help=params option(s): "[^.]$" absent from output: "y"
FAIL: compiler driver --help=param option(s): "^ +-.*[^:.]$" absent from output: "  --param-ipa-jump-function-lookups= Maximum number of statements visited during jump function offset discovery"

2020-10-15  Jakub Jelinek  <jakub@redhat.com>

	* params.opt (-param-ipa-jump-function-lookups=): Add full stop at
	the end of the parameter description.