The following header files are present multiple times in the directories
list.
rtnhdr.h sr_unix sr_unix_nsb
zbreaksp.h sr_unix sr_i386
emit_code.h sr_port sr_i386
auto_zlink.h sr_unix sr_i386
obj_filesp.h sr_unix sr_unix_nsb
opcode_def.h sr_port sr_unix_nsb
This over lap meant that a #include "header.h" chose the header in the
same directory as a C file instead of the one listed in the compile line
include directory listing.