ANDROID: Incremental fs: Separate pseudo-file code

Also fixed two bugs in the process:

is_pseudo_filename was not previously checking for .log, so an attempt
to create a .log would succeed.

All ioctls could be called on all files. ioctls now set on the correct
files.

Bug: 162856396
Test: incfs_test passes
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Change-Id: I25bab8a592e1a7c30fa97d864de6326e6ac12f26