Avoid holding on lots of data with C++ Find Usages

The snapshots at the moment of search were held as long as the
corresponding search result panel was kept, to allow mapping of the old
symbol to the corresponding symbol in the new snapshot.
Now we just save the file name and ID of the old symbol.

Change-Id: Iaf3c9ca27ec2b788f142bd0dd6b86e34e66d5c8b
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
Android: Remove bestMatch calls in fallback code in buildTargetSDK

besdtMatch finds a ndk version that is at most the targetApi passed into it.
Since we are passing in the fallback and lowest possible api level that qt
supports, the function would return at most the lowest supported version.
That's not very useful and cannot have worked, so simpy return the fallback
version directly.

Change-Id: I5e4757639099af4d207f928b0335d28efd75a02b
Reviewed-by: BogDan Vatra <bogdan@kde.org>
Android: Distinguish between platforms in the ndk and the sdk

The available platforms in the ndk might not be the same as in the sdk.
This patch is renames everything using the ndk platform list to
ndkPlatforms, except the highestAvailablePlatform which wrongly uses
the ndk platform list.

Change-Id: I02d9b68bbc27b0c748281678fe654d5f4244578d
Reviewed-by: BogDan Vatra <bogdan@kde.org>
Android: Rework sdkTargets() to cache the output of adb

Also rename/change highestAvailablePlatform to highestAvailableSdk.
This fixes a bug reported on irc, where the lists for sdk and ndk
were different and the highestAvailablePlatform was not available
as in the sdk.

Change-Id: I17fec9e8ce1913e933ddcf8eaa21d6bb6e14c5be
Reviewed-by: BogDan Vatra <bogdan@kde.org>