C++: Compilation with recent C++ compiler needs an overloaded delete[] operator that includes a size_t size argument.

ARM: The older ARM7 and ARM9 configurations were determining CFLAGS based on the GCC version 4.x.x or not.  That needx to be extended for 5.x.x and 6.x.x which also behave like 4.x.x.

C++: Compilation with recent C++ compiler needs an overloaded delete operator that includes a size_t size argument.

procfs routing table:  Don't print the IPv4 routing table header if the table is empty.  Fix a couple of places where CONFIG_NET_IPv4 was used wehre IPv6 was intended (not noticed now because I am testing with both enabled).

cwchar:Use CONFIG_LIBC_WCHAR to only export the wc/mb functions

Approved-by: Gregory Nutt <gnutt@nuttx.org>

   When a build does not want to use wide or multibyte char
   CONFIG_LIBC_WCHAR is not set. Therefore we should to only
   export the wc/mb functions when defined.

   Regardless of the stat of CONFIG_LIBC_WCHAR the non mb/wc
   definitions such as mbstate_t, wint_t, wctype_t need to be
   exported.

Network routing table:  Trivial name changes to make IPv4 and IPv6 more symmetric.  Add debug logic to dump the content of the router table.

Networking: Fix typo for 802.11 devices in netdev_register().  Was being masked before because depended on CONFIG_NET_MULTLINK.

Fix IPv6 loopback driver that depended on the removed g_ipv6_allonesaddr.  Noted by Masayuki Ishikawa

readme: fix typo Bask->Bash

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Networking:  Fix netdev_dev_lladdrsize.  In some configurations, it could return the wrong size for the address of a packet radio.

Remove CONFIG_NET_MULTILINK.  This increases code size by a little, but greatly reduces the complexity of the network code.