t-pdp11: Add MULTILIB support for msoft-float.

t-pdp11: Add MULTILIB support for msoft-float.

        * t-pdp11: Add MULTILIB support for msoft-float.
        * pdp11.h (LEGITIMATE_CONSTANT_P): Fix soft-float case.

        * t-pdp11: Add LIB2FUNCS_EXTRA.
        * pdp11.c (pdp11_output_function_prologue): Restrict offset to 16bit,
        add preceding 0 to the octal constant, rename 'fp' to 'r5', rename
        'fldd' to 'ldd', rename 'fstd' to 'std'.
        (pdp11_output_function_epilogue): Likewise.
        (output_move_quad): Make the comment gas compatible.
        (output_ascii): Add preceding 0 to the octal constant.
        (print_operand_address): Add pre_modify, post_modify.
        (output_addr_const_pdp11): Add preceding 0 to the octal constant.
        * pdp11.h (GO_IF_LEGITIMATE_ADDRESS) : Add 'movb' pre_modify case
        with the indication of Paul Koning.
        (PRINT_OPERAND): Fix floating constant.
        * pdp11.md (movdi): Restrict matching pattern.
        (movqi): Generalize the matching pattern.
        (movdf): Restrict matching pattern.
        (zero_extendqihi2): Change constant representation.
        (floatsidf2): Fix wrong operands.
        (addqi3): Fix wrong instruction name.
        (subqi3): Fix wrong instruction name.
        (andsi3, andhi3, andqi3): Simplify and fix to use 'bic'.
        (xorsi3): Fix wrong insn.
        (one_cmplqi2): Add two operand pattern.
        (lsrsi3): New.
        (negsi2): New.
        (call): Add register indirect case.
        (mod): Fix wrong subreg.

From-SVN: r57886