Makefile: Remove 'make torture' target

The test executor is too simplistic and needs more work.  Having a JVM
test harness is useful but probably makes more sense out of tree.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
x86-64: Fix native_call() for float arguments

Signed-off-by: Pekka Enberg <penberg@kernel.org>
x86-64: Switch to GCC -O3 optimization level

Signed-off-by: Pekka Enberg <penberg@kernel.org>