In libevent 2.2 dev, libevent is sliced into base, _core and _extra
libraries. libevent_pthreads on gcc exhibits a dependency on the
libevent_core lib. The resulting error prior to this patch is;
ERROR: /home/pivotal/workspace/envoy/test/common/http/BUILD:109:1:
Linking of rule '//test/common/http:codes_speed_test' failed (Exit 1)
gcc failed: error executing command /usr/bin/gcc
@bazel-out/k8-fastbuild/bin/test/common/http/codes_speed_test-2.params
bazel/foreign_cc/event/lib/libevent_pthreads.a(evthread_pthread.c.o):evthread_pthread.c:function
evthread_posix_lock_alloc: error: undefined reference to 'event_mm_malloc_'
bazel/foreign_cc/event/lib/libevent_pthreads.a(evthread_pthread.c.o):evthread_pthread.c:function
evthread_posix_lock_alloc: error: undefined reference to 'event_mm_free_'
bazel/foreign_cc/event/lib/libevent_pthreads.a(evthread_pthread.c.o):evthread_pthread.c:function
evthread_posix_lock_free: error: undefined reference to 'event_mm_free_'
bazel/foreign_cc/event/lib/libevent_pthreads.a(evthread_pthread.c.o):evthread_pthread.c:function
evthread_posix_cond_alloc: error: undefined reference to 'event_mm_malloc_'
bazel/foreign_cc/event/lib/libevent_pthreads.a(evthread_pthread.c.o):evthread_pthread.c:function
evthread_posix_cond_alloc: error: undefined reference to 'event_mm_free_'
bazel/foreign_cc/event/lib/libevent_pthreads.a(evthread_pthread.c.o):evthread_pthread.c:function
evthread_posix_cond_free: error: undefined reference to 'event_mm_free_'
bazel/foreign_cc/event/lib/libevent_pthreads.a(evthread_pthread.c.o):evthread_pthread.c:function
evthread_use_pthreads: error: undefined reference to 'evthread_set_lock_callbacks'
bazel/foreign_cc/event/lib/libevent_pthreads.a(evthread_pthread.c.o):evthread_pthread.c:function
evthread_use_pthreads: error: undefined reference to 'evthread_set_condition_callbacks'
bazel/foreign_cc/event/lib/libevent_pthreads.a(evthread_pthread.c.o):evthread_pthread.c:function
evthread_use_pthreads: error: undefined reference to 'evthread_set_id_callback'
collect2: error: ld returned 1 exit status
On Windows, including event_extra.lib was excessive/unnecessary.
Signed-off-by: Sunjay Bhatia <sbhatia@pivotal.io>
Signed-off-by: William A Rowe Jr <wrowe@pivotal.io>