Fix a -Wunqualified-std-cast-call warning.

This CL fixes the following warning:
	frameworks/base/libs/hwui/thread/WorkQueue.h:60:25: warning: unqualified call to std::move [-Wunqualified-std-cast-call]

The code in question was checked in in 2017. Probably the warning has
been enabled very recently.

Test: m -j
Change-Id: I1f87bf8f53088a464cd0790305e7803d8c0b59d1