The vendor compilers on both IRIX and HP-UX object to three
spots in header.c, where a void * is cast to some other type and
then a change is made to the pointer (in two cases, pointer
addition)

Reproducible: Always
Steps to Reproduce:
1. configure; make

on IRIX or HP-UX, with the vendor compiler on either.

The IRIX compiler spake thusly:

cc-1133 cc: ERROR File = header.c, Line = 263
  Expression must be a modifiable lvalue.

            for (; ie.info.count > 0; ie.info.count--, ((int_32 *)t) += 1)
                                                                  ^

cc-1133 cc: ERROR File = header.c, Line = 267
  Expression must be a modifiable lvalue.

            for (; ie.info.count > 0; ie.info.count--, ((int_16 *)t) += 1)
                                                                  ^

cc-1133 cc: ERROR File = header.c, Line = 302
  Expression must be a modifiable lvalue.

            ei = (int_32 *) *p = xmalloc(count);
                  ^
                  
The HP-UX compiler says:

cc: "header.c", line 263: warning 524: Cast (non-lvalue) appears on
left-hand side of assignment.
cc: "header.c", line 263: error 1549: Modifiable lvalue required for
assignment operator.
cc: "header.c", line 267: warning 524: Cast (non-lvalue) appears on
left-hand side of assignment.
cc: "header.c", line 267: error 1549: Modifiable lvalue required for
assignment operator.
cc: "header.c", line 302: warning 524: Cast (non-lvalue) appears on
left-hand side of assignment.
cc: "header.c", line 302: error 1549: Modifiable lvalue required for
assignment operator.


The Compaq compiler on Tru64 also points out those three lines as
questionable, but it lets them off with just a warning.