Fixes from static analysis
Robert Sprowson authored
Ref https://www.riscosopen.org/forum/forums/4/topics/9503#posts-72595 and subsequent offline checks.

arp: missing return from non-void delete() (from FreeBSD 13977)
ifconfig: undefined variable m (from FreeBSD revision 13145)
          correct return types to void for xxx_getaddr() (from FreeBSD revision 19914)
inetstat: dead array variable buf2[] removed
ipvars: missing return value from main()
map-mbone: missing va_end (from NetBSD revision 1.8)
md5: file handle leak on error (from FreeBSD revision 292955)
mrinfo: missing va_end (from NetBSD revision 1.12)
mtrace: missing va_end (from NetBSD revision 1.18)
newfiler: add comment for apparent missing return
sysctl: fix QUAD variable type (from FreeBSD revision 88696)
        though academic since Internet doesn't have any quad_t variables explicit function return types added in PathConf.c
BootNet: change RMIfThere alias to use temporary variable from its own namespace

Version 5.61. Tagged as 'Internet-5_61'
698cbb29