Updates for Qt 5.12 and 64 bit

Add support for Linux and experimenting with settings (there are "set" but no "get" options for them though)

Add support for specifying fixed RTK base position

And fix build error…

-GIT_TAG is redundant
-closes #4023

* travis-ci try ccache on OSX and android

* travis-ci ccache stats

* try again

* Attempt to prepend ccache to qmake command

* Test enabling ccache for ios too

* Deploy ccache from S3 per @dagar

* Revert "Test enabling ccache for ios too"

It was a nice thought.

This reverts commit 7e7aeb367696ee9c8abc5cc8122dcd35196d96bb.

* Try to optimally set the number of make jobs

* Fix job estimation and disable ccache on android

* Android: reenable ccache and disable parallel jobs

* Check if android build passes with 4 workers

* Try to parallelize xcodebuild too

* Give mac builders an extra worker and pretty up the ios build output

* Add make output filtering with correct exit code, no sudo or ccache on ios build

* Try wrapping ccache to enable use on xcodebuild

* Make ios ccache helpers executable

* Turn back on pretty printing for IOS

* Show some ccache stats on IOS build to see if we're getting hits

* Change android build OS type to linux

* Require trusty for android build

* Require sudo for android so we get trusty

* Maybe this will function properly on edge?

* Try to use stripped binary bzips

* Screw it! Run android on precise again

* Back to the original android build configuration. I give up

* [WIP] deploy release and daily build pdbs to s3

* First pass at windows symbol generation for #2680

* Kill the conflicted compiler flag warning

* Tweaks to windows compiler flags for release builds, more qt-ish release symbols and ltcg

* Deploy tagged release symbols and CI builds to different S3 folders

* Support LTCG on iOS

* Just turn off ltcg for iOS if it is going to be such a pain