Add mcbasher

Add back a new mcbasher (built on folly this time) which generate
load to a memcached node

Usage:
    mcbasher --host localhost \
             --user myuser \
             --password mypassword \
             --bucket mybucket \
             --connections 100 \
             --threads 4
             --pipeline \
             --ooo

Creates 4 threads with 100 connections using OoO and pipelines
data to hammer the server.

Instead of --pipeline and --ooo one may use --disconnect which
insert disconnects into the mix of operations to send to the
server.

Change-Id: I6b3845f70da35f816de7d331a4b3683d2e579716
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/165330
Tested-by: Build Bot <build@couchbase.com>
Reviewed-by: Dave Rigby <daver@couchbase.com>

programs/CMakeLists.txt

@@ -21,6 +21,7 @@ add_subdirectory(dcpdrain)
 add_subdirectory(dcplatency)
 add_subdirectory(engine_testapp)
 add_subdirectory(kvlite)
+add_subdirectory(mcbasher)
 add_subdirectory(mcctl)
 add_subdirectory(mcifconfig)
 add_subdirectory(mclogsplit)

programs/mcbasher/CMakeLists.txt

@@ -0,0 +1,4 @@
+cb_add_test_executable(mcbasher mcbasher.cc $<TARGET_OBJECTS:mc_program_utils>)
+kv_enable_pch(mcbasher)
+target_link_libraries(mcbasher PRIVATE mc_client_connection mcd_util platform)
+add_sanitizers(mcbasher)