Forward SIGTERM to spawned child process
Forward SIGTERM to spawned child process

Signed-off-by: Brendan Dixon <e9401a09b1612f6a181940f70779b7a4ece5c52c@microsoft.com>

andyliuliming/WALinuxAgent,andyliuliming/WALinuxAgent,hglkrijger/WALinuxAgent,hglkrijger/WALinuxAgent,Azure/WALinuxAgent,Azure/WALinuxAgent,rjschwei/WALinuxAgent,rjschwei/WALinuxAgent