connmgr: Count unsent async messages. #1800

Job	Run time
linux deb no dpdk	7m 9s
osx clang --disable-ssl	4m 8s
dpdk gcc	7s
linux gcc --disable-ssl	3m 12s
linux clang --disable-ssl	3m 43s
linux gcc test	10m 7s
linux clang test asan	17m 38s
linux clang test ubsan	12m 18s
linux gcc test --enable-shared	18m 37s
linux clang test --enable-shared	17m 23s
linux gcc test dpdk	12m 48s
linux clang test dpdk	9m 49s
linux gcc test -ljemalloc	10m 23s
linux clang test -ljemalloc	11m 4s
linux gcc --enable-afxdp	3m 46s
linux clang --enable-afxdp	3m 27s
linux gcc dpdk --enable-shared	5m 6s
linux clang dpdk --enable-shared	5m 25s
linux gcc dpdk-shared	4m 30s
linux clang dpdk-shared	3m 16s
linux gcc dpdk-shared --enable-shared	5m 3s
linux clang dpdk-shared --enable-shared	3m 57s
linux gcc m32 --disable-ssl	4m 9s
	2h 57m 5s

Provide feedback