Fix CTS com.android.cts.filesystemperf.RandomRWTest#testRandomRead Seldom fail

The test case will caluate target disk size using current memory size and free disk size in function getFileSizeExceedingMemory(). 
A special boundary condition may happen, when target disk size(memory size*2) == disk free size  >= 512 MB, 
any process write data to disk will cause java.io.IOException: write failed: ENOSPC (No space left on device).
So suggest reserve 50MB disk space for saving log or other process using.

Change-Id: I1003f9a6f74b6aa6b4c46d6e712a69b4f424772b
Signed-off-by: Junjie Hu <junjie.hu@mediatek.com>
1 file changed