ASSERT gbop-test arch_exports.h:2063 extract_branchtype()

This happened once on Appveyor:

https://ci.appveyor.com/project/DynamoRIO/dynamorio/build/1.0.1993
```
[00:05:02] 65/246 Test #62: code_api|security-win32.gbop-test ............................***Failed Required regular expression not found.Regex=[^plain C call
[00:05:02] ?
[00:05:02] res=kernel32_base
[00:05:02] ?
[00:05:02] plain asm call
[00:05:02] ?
[00:05:02] res=kernel32_base
[00:05:02] ?
[00:05:02] pretend on stack
[00:05:02] ?
[00:05:02] exception since not cleaning up stack
[00:05:02] ?
[00:05:02] res=kernel32_base
[00:05:02] ?
[00:05:02] pretend on flushed stack
[00:05:02] ?
[00:05:02] exception since not cleaning up stack
[00:05:02] ?
[00:05:02] res=kernel32_base
[00:05:02] ?
[00:05:02] pretend in image but not after call
[00:05:02] ?
[00:05:02] res=kernel32_base
[00:05:02] ?
[00:05:02] JMP allowed!
[00:05:02] ?
[00:05:02] done
[00:05:02] ?
[00:05:02] $
[00:05:02] ] 0.29 sec
[00:05:02] plain C call
[00:05:02] res=kernel32_base
[00:05:02] plain asm call
[00:05:02] res=kernel32_base
[00:05:02] pretend on stack
[00:05:02]
```