Enable compile-time override for MAXTCPLISTENPORTS

MAXTCPLISTENPORTS controls the permitted number of http(s)_port which
may be configured. The hard-coded default is 128 ports.

This patch enables the use of CXXFLAGS="-DMAXTCPLISTENPORTS=n" to set a
new limit when building Squid.
Deprecate tag ACL type in favour of note