init: Change umask of forked processes to 077

Modify init to set the umask to 077 when forking processes.
This helps protect against inadvertant information disclosure
in init's child processes.

ueventd: Keep umask at 000. uevent needs to be able to
create device nodes with exactly the permissions it
indicates.

Testing:
1) Do an "ls -lR /data /dev" on the device before and after
the umask change and diff the output. Verified by hand
that the permission change wouldn't cause any problems.

2) Verify that package installation works, and the permissions
are as expected, when installing a program from market and
"adb install".

Bug: 3272072
Change-Id: Ie4f7f06c0ee9da8d9b6fce25d71d8991a9bce406