[LinuxCNC/linuxcnc PR#518] halcompile: Add checks to generated code for array overflows

This checks at ‘loadrt’ time that the dynamic array size fits within
the static maximum size. This would detect problems like demux’s
buggy “pin out bit out-## [1:personality]” which would allocate space
for at most 1 pin. Now, this generates an error like

halcmd: loadrt demux count=1 personality=32
Note: Using POSIX non-realtime
Pin out-##: Requested size 32 exceeds max size 1
demux: rtapiappmain: No space left on device (-28)

(This doesn’t add any runtime checking of the accesses like out(i) = true)