test: process: Initialise member variables

The ProcessTest() declares member variables but leaves them unitialised.
Set them appropriately from the constructor.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

test/process/process_test.cpp

@@ -35,6 +35,7 @@ class ProcessTest : public Test
 {
 public:
 	ProcessTest()
+		: exitStatus_(Process::NotExited), exitCode_(-1)
 	{
 	}