Buck: Package servlet-api in WEB-INF/pgm-lib again

Idc8c24854 added servlet-api as transitive dependency to gerrit-server
Buck artifact. As the consequence servlet-api was included in lib
drectory instead of in pgm-lib.

Change-Id: I190a4d98d85d17b619ee81e3bb32eee58134677c
1 file changed