Remove the xaddroff ComplexPattern.

The xaddroff pattern is currently (mistakenly) used to recognize
the *base* register in pre-inc store patterns.  This patch replaces
those uses by ptr_rc_nor0 (as is elsewhere done to match the base
register of an address), and removes the now unused ComplexPattern.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177731 91177308-0d34-0410-b5e6-96231b3b80d8