debuggerd seccomp: explain why we define PROT_READ/WRITE.

Add a comment explaining why we define PROT_READ/PROT_WRITE, even
though a current libminijail supports both cosntants.

Bug: http://b/73273658
Test: treehugger
Change-Id: I51c1be1b1b569e94dbc9045a90bc28221b7dc9c7
1 file changed