Don't protect malloc call with system mutex in main server loop.

Not required to synchronize malloc calls, it's threadsafe on all supported platforms.

This partially backports f55a6610fbfcd078c1e2a58cd0da94efef35cc2d
(cherry picked from commit 5e0e6bd6575403de7758a019866c490ab2a39e30)

Conflicts:

	src/server.c
Increase the threshold for DDOS detection and apoptosis. We now need 3 x maxthreads connections to be dropped while none of the existing ones actually finish.
Merge pull request #657 from jimis/3.3.x-apoptosis_harder

Increase the threshold for DDOS detection and apoptosis. We now need 3 x...