Various fixes (memory leak & crash) in the OpenCL interpreter code.

Pre-compiling of OpenCL kernel is disabled with this change.

(cherry picked from commit b981c089a9194f33b46272e3f4efa117241ea533)
(cherry picked from commit e253d46af3b47afd0006084bec89b02473ee457a)
(cherry picked from commit 0d7f89b021f1354a0fa607862296b11c9fd8a4dd)
(cherry picked from commit 5325137783825c498ed4236080ed7fe51cdec09a)
(cherry picked from commit 20ed6886ade81ee015a22b2eb3aeff64691971bf)
(cherry picked from commit 7a0ed3a406bd14bb2b52c383282daf4777ba76e0)

Conflicts:
	sc/source/core/data/formulacell.cxx

Change-Id: Iae97f4f877c329f443c7d222c6a2016678af2387
Reviewed-on: https://gerrit.libreoffice.org/8496
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Initialize OpenCL device on the main thread when pre-compiling kernels.

Else it would cause extremely hard-to-debug random crashes when interpreting
formulas with OpenCL.

And let's re-enable kernel pre-compilation with this fix.

Change-Id: Ib104bfdc3f56a02c052c837eb4bf3ecc95d562e0
(cherry picked from commit 6e24c789572aba5b6ee95e894f6d778777b1df58)
Reviewed-on: https://gerrit.libreoffice.org/8498
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>