illumos gate

When writing unit tests for #14011, I discovered that the existing mov Moffs, %eax and mov %eax, Moffs emulation (from which I based the movb Moffs, %al addition) is not properly handling calculation of the linear address. The conditions which precipitated the need for #14011 were somewhat unusual, and further measurement suggests that this whole class of instruction (mov with a Moffs operand) are very rarely used.