validating successful malloc for lastLocation and classes

[emawby]

Whenever we use malloc we should validate that it was successful since it could fail. Failing would cause a crash by trying to use an object that is actually NULL.
Fixes #967

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This change is 

[jkasten2]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @emawby, @Jeasmine, and @nan-li)

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-- commits, line 1 at r1 ([raw file](https://github.com/onesignal/onesignal-ios-sdk/blob/03d69ae9a7822a5c693f25982631d70600367c62/-- commits#L1)):
Remove this Commits file.

[jkasten2]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @emawby, @Jeasmine, and @nan-li)

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-- commits, line 1 at r1 ([raw file](https://github.com/onesignal/onesignal-ios-sdk/blob/03d69ae9a7822a5c693f25982631d70600367c62/-- commits#L1)):

Previously, jkasten2 (Josh Kasten) wrote…

Remove this Commits file.

Never mind, this isn't showing up in Github so this is a Reviewable only change / bug.

[jkasten2]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @emawby, @Jeasmine, and @nan-li)