ANDROID: 16K: Fix mincore emulation

Since the temporary page to process the mincore range is reused
and __collapse_mincore_results() bitwise ORs X contiguous entries
with the initial buffer value; clear the previous results when
emulating the page size to avoid corruption from the previous
processed entries.

Bug: 390505059
Bug: 385169772
Bug: 390404912
Test: atest
     vts_ltp_test_x86_64:syscalls.mlock201_64bit#syscalls.mlock201_64bit
          --iterations 10
Change-Id: I816b8952f8d544ab37298582e626ab3f8bbcab7f
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>