Minor fixes

[jakobbotsch]

Switch local morph to use its semantic reasoning about addresses in the GT_EQ/GT_NE cases. Add a missing return false.

[jakobbotsch]

With this we manage to reduce the case in dotnet#9118 to

; Assembly listing for method C:Main():int (FullOpts)
; Emitting BLENDED_CODE for X64 with AVX - Windows
; FullOpts code
; optimized code
; rsp based frame
; partially interruptible
; No PGO data
; 1 inlinees with PGO data; 3 single block inlinees; 1 inlinees without PGO data
; Final local variable assignments
;
;  V00 OutArgs      [V00    ] (  1,  1   )  struct (32) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace"
;* V01 tmp1         [V01,T00] (  0,  0   )     ref  ->  zero-ref    class-hnd exact single-def "NewObj constructor temp" <ObjectEqualityComparer`1[int]>
;* V02 tmp2         [V02    ] (  0,  0   )   ubyte  ->  zero-ref    "Inline return value spill temp"
;* V03 tmp3         [V03    ] (  0,  0   )     int  ->  zero-ref    ld-addr-op "Inlining Arg"
;* V04 tmp4         [V04    ] (  0,  0   )    long  ->  zero-ref    class-hnd exact "Single-def Box Helper" <System.Int32>
;* V05 tmp5         [V05    ] (  0,  0   )   ubyte  ->  zero-ref    "Inline return value spill temp"
;* V06 tmp6         [V06    ] (  0,  0   )    long  ->  zero-ref    class-hnd exact "Inlining Arg" <System.Int32>
;* V07 tmp7         [V07    ] (  0,  0   )  struct (16) zero-ref    do-not-enreg[SF] "stack allocated boxed value class temp" <System.Collections.Generic.KeyValuePair`2[long,int]>
;* V08 tmp8         [V08    ] (  0,  0   )    long  ->  zero-ref    "V07.[000..008)"
;* V09 tmp9         [V09    ] (  0,  0   )     int  ->  zero-ref    "V07.[008..012)"
;
; Lcl frame size = 40

G_M46144_IG01:  ;; offset=0x0000
       sub      rsp, 40
                                                ;; size=4 bbWeight=1 PerfScore 0.25
G_M46144_IG02:  ;; offset=0x0004
       mov      eax, 100
                                                ;; size=5 bbWeight=1 PerfScore 0.25
G_M46144_IG03:  ;; offset=0x0009
       add      rsp, 40
       ret
                                                ;; size=5 bbWeight=1 PerfScore 1.25

; Total bytes of code 14, prolog size 4, PerfScore 1.75, instruction count 4, allocated bytes for code 14 (MethodHash=cd934bbf) for method C:Main():int (FullOpts)
; ============================================================

Looks like we don't manage to remove the frame entirely since we don't get rid of the heap allocation until post-lower DCE, so there is still a helper call during lowering when we're figuring out how much outgoing arg space we need.