Add a judgment condition(>API 26) when calling "FragmentManager.isSta…

[CaiPeng]

Add a judgment condition(>API 26) when calling "FragmentManager.isStateSaved" method.

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[CaiPeng]

I signed it!

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CLAs look good, thanks!

[samtstern]

@CaiPeng can you explain a bit why this addition is needed?

[CaiPeng]

When the dialog is shown, I clicked the denied button, and then my App crashed.
The log shows：
java.lang.NoSuchMethodError: No virtual method isStateSaved()Z in class Landroid/support/v4/app/FragmentManager; or its super classes (declaration of 'android.support.v4.app.FragmentManager' appears in /data/app/.../split_lib_dependencies_apk.apk:classes2.dex) at pub.devrel.easypermissions.RationaleDialogFragmentCompat.showAllowingStateLoss(RationaleDialogFragmentCompat.java:48) at pub.devrel.easypermissions.helper.BaseSupportPermissionsHelper.showRequestPermissionRationale(BaseSupportPermissionsHelper.java:43)

[samtstern]

The FragmentManager in the class you're modifying here comes from the support library. The isStateSaved method was added in support lib 26.0.1:
https://developer.android.com/reference/android/support/v4/app/FragmentManager#isstatesaved

What are your app dependencies? Are you using a lower support library level? I don't think adding an SDK version check should matter here.

[samtstern]

@CaiPeng I am going to close this since it been a few weeks without a response and I can't see the motivation for this PR, however if you have more information please let me know and I will re-open.

Thanks for the contribution!