Add some missing encodings in the ARM integrated assembler.

tests_lit/assembler/arm32/rsb.ll

 ; Show that we know how to translate rsb. Uses shl as example, because it
-; uses rsb for type i64
+; uses rsb for type i64.
+
+; Also shows an example of a register-shifted register (data) operation.
   
 ; REQUIRES: allow_dump
 
 ; Compile using standalone assembler.
 ; RUN: %p2i --filetype=asm -i %s --target=arm32 --args -Om1 \
 ; RUN:   | FileCheck %s --check-prefix=ASM
 
 ; Show bytes in assembled standalone code.
 ; RUN: %p2i --filetype=asm -i %s --target=arm32 --assemble --disassemble \
 ; RUN:   --args -Om1 | FileCheck %s --check-prefix=DIS
@@ skipping 99 matching lines @@
 ; IASM-NEXT:    .byte 0xe5
 
 ; ****** Here is the example of rsb *****
 ; ASM-NEXT:     rsb     r3, r2, #32
 ; DIS-NEXT:  2c:        e2623020
 ; IASM-NEXT:    .byte 0x20
 ; IASM-NEXT:    .byte 0x30
 ; IASM-NEXT:    .byte 0x62
 ; IASM-NEXT:    .byte 0xe2
 
+; ASM-NEXT:    lsr     r3, r0, r3
+; DIS-NEXT:  30:        e1a03330
+; IASM-NEXT:    .byte 0x30
+; IASM-NEXT:    .byte 0x33
+; IASM-NEXT:    .byte 0xa0
+; IASM-NEXT:    .byte 0xe1
+
+; ***** Here is an example of a register-shifted register *****
+; ASM-NEXT:    orr     r1, r3, r1, lsl r2
+; DIS-NEXT:  34:        e1831211
+; IASM-NEXT:    .byte 0x11
+; IASM-NEXT:    .byte 0x12
+; IASM-NEXT:    .byte 0x83
+; IASM-NEXT:    .byte 0xe1
+
   ret i64 %result
 }