fortran: change subrange enum to bit field

fortran: change subrange enum to bit field

Change Fortran subrange enum for subrange expressions to
represent a bitfield for easier manipulation.  Consequently
also change occurences and evaluation of said enum.  The
behaviour of GDB is unchanged.

2013-11-27  Christoph Weinmann  <christoph.t.weinmann@intel.com>

	* eval.c (value_f90_subarray): Change evaluation of the
	subarray boundaries.  Set boundaries to be either user
	provided (bit in range_type was set), or take the default
	value if the boundary was not provided by the user.
	* expprint.c (print_subexp_standard): Alter boundary com-
	putations to use updated range_type enum.
	* expprint.h (dump_subexp_body_standard): Dito.
	* expression.h (range_type): Change the enum to use bit
	values for each boundary, if set by the user.
	* f-exp.y (subrange): Change rules for subrange expressions
	to write the relevant bit sequence onto the elt stack.
	* parse.c (operator_length_standard): In case of OP_RANGE
	change the calculation of the number of	arguments on the
	elt stack, depending on the number of boundaries provided
	by the user.
	* rust-exp.y (convert_ast_to_expression): Modify calcula-
	tion of subscript elements to use altered range_type.
	* rust-lang.c (rust_range): Dito.
	* rust-lang.c (rust_subscript): Dito.

Signed-off-by: Christoph Weinmann <christoph.t.weinmann@intel.com>