Remove trap code from disassembly.

Summary:
NativeProcessProtocol uses ReadMemory internally for setting/checking
breakpoints but also for generic memory reads (Handle_m), this change adds a
ReadMemoryWithoutTrap for that purpose. Also fixes a bunch of misuses of addr_t
as size/length.

Test Plan: `disassemble` no longer shows the trap code.

Reviewers: jingham, vharron, clayborg

Reviewed By: clayborg

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D9330

llvm-svn: 236132