[LLDB][MIPS] Handle false positives for MIPS hardware watchpoints

    SUMMARY:
    Last 3bits of the watchpoint address are masked by the kernel. For example, n is 
    at 0x120010d00 and m is 0x120010d04. When a watchpoint is set at m, then watch 
    exception is generated even when n is read/written. To handle this case, instruction 
    at PC is emulated to find the base address of the load/store instruction. This address 
    is then appended to the description of the stop-info packet. Client then reads this 
    information to check whether the user has set a watchpoint on this address.
    
    Reviewers: jingham, clayborg
    Subscribers: nitesh.jain, mohit.bhakkad, sagar, bhushan and lldb-commits
    Differential Revision: http://reviews.llvm.org/D11672

llvm-svn: 244864