saving a raw bndb loses platform information

[psifertex]

Version and Platform (required):

• Binary Ninja Version: As far back as 3.0 up to latest dev as of today

Bug Description:
Platform information is lost.

Steps To Reproduce:

1. Open a new tab
2. Compile some SCC shellcode for any platform
3. Create a function using p of the same arch and platform
4. Using the python console confirm that a bv.platform is set (it is)
5. Save the current analysis database to a BNDB
6. Re-open the BNDB
7. Observe that bv.platform is not set using the console

Expected Behavior:
The platform should still be set

This has potentially obnoxious implications for users doing firmware analysis depending on the workflow. The saving grace/work-around is that the mapped view does not have this problem so if you first save the shellcode, then open the file and use the default open-with-options mapped view, you'll be able to create a platform, save the BNDB and re-open without losing the platform.

[lwerdna]

This is also needed to support the set-default-arch-menu branch which a component in the upcoming arm/thumb function creation solution: #1177 (comment)

[bpotchik]

'Raw' BinaryViews should not have a platform set. Also, any analysis that needs to be performed should occur in the context of a BinaryView that is created by a loader.

The workflow above should probably be modified to automatically create a mapped view for you.