libprocessgroup users use libcutils

libprocessgroup symbols are being moved into libcutils in order to
optimize linking/memory usage. libprocessgroup will no longer be
required in the future (however removing references to it will come
separately).

Bug: 135145426
Test: boot

Test:
BEFORE:
$ adb shell showmap -a $(pid hwservicemanager) | grep -P "libprocessgroup|libcutils" -A1 | grep -P 'libprocessgroup|libcutils|\.bss' | awk '{s += $9}END{print s}'
28

AFTER:
$ adb shell showmap -a $(pid hwservicemanager) | grep -P "libprocessgroup|libcutils" -A1 | grep -P 'libprocessgroup|libcutils|\.bss' | awk '{s += $9}END{print s}'
12

Change-Id: I10d7c2d2b2b14cbbe0a128b9156d31206419d24c