libsuspend: compile as a static library

Compile libsuspend as a static library as well, currently needed by the charger
code in some cases.

Related-to-bug: 7429504
Change-Id: I113017c2c855f915b77c76d8934b6e57c0bb532c
Signed-off-by: Iliyan Malchev <malchev@google.com>