search for: fieldoffsetinbits

Please review this patch for PR3510 (and <rdar://problem/6564697>). The bug is a failure to handle a "hole" inside an initialized structure, where the hole may be induced by a designated initializer or by alignment: http://llvm.org/bugs/show_bug.cgi?id=3510 The original code was greatly simplified by using FieldNo to index the LLVM fields and the initializer in