BitmapTest: Fix initial memory measurement

There is a Surface created for a testDrawingHardwareBitmapNotLeaking
test.
Buffers allocated for the bufferqueue for this surface
are not allocated as Surface is created, but on demand.
That make it possible for some buffers being allocated
a way later then two first cycles.

Test: this
Merged-In: I721c8bd0c03d99cb49903b3c3a83134d52d65ff9
Change-Id: I721c8bd0c03d99cb49903b3c3a83134d52d65ff9
1 file changed