Fortran: Replace simple '.' quotes by %<.%>

Fortran: Replace simple '.' quotes by %<.%>

When using %qs instead of '%s' or %<=%> instead of '=' looks nicer
by having nicer quotes and bold text, if the terminal supports it;
otherwise, plain quotes are used.

gcc/fortran/ChangeLog:

	* match.cc (gfc_match_member_sep): Use %<...%> in gfc_error.
	* openmp.cc (gfc_match_oacc_routine, gfc_match_omp_context_selector,
	gfc_match_omp_context_selector_specification,
	gfc_match_omp_declare_variant, resolve_omp_clauses): Likewise;
	use %qs instead of '%s'.
	* primary.cc (match_real_constant, gfc_match_varspec): Likewise.
	* resolve.cc (gfc_resolve_formal_arglist, resolve_operator,
	resolve_ordinary_assign): Likewise.