objc2_analyzer.py cannot work for IDA 7.5

[zhengmin1989]

There are some changes in IDA 7.*. For example:

1. "ADRP Rx, label@PAGE; ADD Rx, Rx, label@PAGEOFF" is replaced by "ADRL Rx, label"

2. without idaapi.auto_wait(), python script cannot get Xref.

Please update objc2_analyzer.py to support IDA 7.*. Thank you.