tests: Fix a -Wbad-function-cast warning in the atomic tests
Assigning the gpointer return value from g_atomic_pointer_get() to a gsize variable was not making -Wbad-function-cast happy. Assign to an intermediate gpointer variable and then cast that instead.
Signed-off-by: Philip Withnall firstname.lastname@example.org
Closes #1475 (closed)
Untested on armel. Needs testing on the Debian builders.