AVR: PR122505 - Fix bloated mulpsi3 in the wake of hacking around PR118012.

AVR: PR122505 - Fix bloated mulpsi3 in the wake of hacking around PR118012.

Since the PR118012 work-around patch, there is an SImode insn also for
the non-MUL case, but there is no mulpsi3.  This makes the middle-end
use the mulsi3 insn for 24-bit multipications like in:

__uint24 mul24 (__uint24 a, __uint24 b)
{
    return a * b;
}

which will be compiled to:

mul24:
    push r28         ;  34  [c=4 l=1]  pushqi1/0
    push r29         ;  35  [c=4 l=1]  pushqi1/0
    in r28,__SP_L__  ;  47  [c=4 l=2]  *movhi/7
    in r29,__SP_H__
    sbiw r28,8   ;  48  [c=8 l=1]  *addhi3/2
    in __tmp_reg__,__SREG__  ;  38  [c=8 l=5]  movhi_sp_r/2
    cli
    out __SP_H__,r29
    out __SREG__,__tmp_reg__
    out __SP_L__,r28
/* prologue: function */
/* frame size = 8 */
/* stack size = 10 */
    std Y+1,r22  ;  49  [c=4 l=1]  movqi_insn/2
    std Y+2,r23  ;  50  [c=4 l=1]  movqi_insn/2
    std Y+3,r24  ;  51  [c=4 l=1]  movqi_insn/2
    std Y+5,r18  ;  52  [c=4 l=1]  movqi_insn/2
    std Y+6,r19  ;  53  [c=4 l=1]  movqi_insn/2
    std Y+7,r20  ;  54  [c=4 l=1]  movqi_insn/2
    ldd r18,Y+1  ;  55  [c=4 l=1]  movqi_insn/3
    ldd r19,Y+2  ;  56  [c=4 l=1]  movqi_insn/3
    ldd r20,Y+3  ;  57  [c=4 l=1]  movqi_insn/3
    ldd r21,Y+4  ;  58  [c=4 l=1]  movqi_insn/3
    ldd r22,Y+5  ;  59  [c=4 l=1]  movqi_insn/3
    ldd r23,Y+6  ;  60  [c=4 l=1]  movqi_insn/3
    ldd r24,Y+7  ;  61  [c=4 l=1]  movqi_insn/3
    ldd r25,Y+8  ;  62  [c=4 l=1]  movqi_insn/3
    call __mulsi3    ;  33  [c=20 l=2]  *mulsi3_call_pr118012
/* epilogue start */
    adiw r28,8   ;  63  [c=8 l=1]  *addhi3/2
    in __tmp_reg__,__SREG__  ;  42  [c=8 l=5]  movhi_sp_r/2
    cli
    out __SP_H__,r29
    out __SREG__,__tmp_reg__
    out __SP_L__,r28
    pop r29      ;  43  [c=4 l=1]  popqi
    pop r28      ;  44  [c=4 l=1]  popqi
    ret

where the expected code is simply:

mul24:
    call __mulpsi3   ;  9   [c=20 l=2]  call_value_insn/1
/* epilogue start */
    ret      ;  24  [c=0 l=1]  return

The patch just allows the mulpsi3 insn for the non-MUL case, except for
AVR_TINY which passes the 2nd argument on the stack so no insn can be used.

The change might be beneficial even in the absence of PR118012 because
the __mulpsi3 footprint is leaner than a libcall.

	PR tree-optimization/118012
	PR tree-optimization/122505
gcc/
	* config/avr/avr.md (mulpsi3): Also allow the insn condition
	in the case where avropt_pr118012 && !AVR_TINY.
	(*mulpsi3): Handle split for the !AVR_HAVE_MUL case.
	(*mulpsi3-nomul.libgcc_split, *mulpsi3-nomul.libgcc): New insns.