COMPMID-1504: (Nightly) Segfaults on CL and android

Keeps a copy of context in Scheduler to avoid releasing KernelLibrary
resources before Scheduler resourses leading to a segfault.
Does not exactly revert COMPMID-1122 as it still tries to keep context
in sync.

Change-Id: I3deb6bc1725b80f65f51ebd34d536f612ef6dd86
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/144024
Reviewed-by: Michele DiGiorgio <michele.digiorgio@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>
diff --git a/src/runtime/CL/CLScheduler.cpp b/src/runtime/CL/CLScheduler.cpp
index a812bad..a311c6f 100644
--- a/src/runtime/CL/CLScheduler.cpp
+++ b/src/runtime/CL/CLScheduler.cpp
@@ -42,7 +42,7 @@
 std::once_flag CLScheduler::_initialize_symbols;
 
 CLScheduler::CLScheduler()
-    : _queue(), _target(GPUTarget::MIDGARD), _is_initialised(false), _cl_tuner(nullptr), _cl_default_static_tuner(nullptr)
+    : _context(), _queue(), _target(GPUTarget::MIDGARD), _is_initialised(false), _cl_tuner(nullptr), _cl_default_static_tuner(nullptr)
 {
 }