driver: Fix redundant descriptions in options

driver: Fix redundant descriptions in options

Addresses issues where the two-column format of options descriptions was
used, but the columns were separated by spaces rather than a single tab,
causing the help output to be more verbose than intended.

gcc/ChangeLog:

2020-03-15  Lewis Hyatt  <lhyatt@gmail.com>

	* common.opt: Avoid redundancy in the help text.
	* config/arc/arc.opt: Likewise.
	* config/cr16/cr16.opt: Likewise.

gcc/c-family/ChangeLog:

2020-03-15  Lewis Hyatt  <lhyatt@gmail.com>

	* c.opt: Avoid redundancy in the help text.

gcc/fortran/ChangeLog:

2020-03-15  Lewis Hyatt  <lhyatt@gmail.com>

	* lang.opt: Avoid redundancy in the help text.

gcc/testsuite/ChangeLog:

2020-03-15  Lewis Hyatt  <lhyatt@gmail.com>

	* gcc.misc-tests/help.exp: Adapt to new output for
	-Walloc-size-larger-than= option.