shcomp: fix redirection with process substitution

The commands within a process substitution used as an argument to a
redirection (e.g. < <(...) or > >(...)) are simply not included in
parse trees dumped by shcomp. This can be verified with a command
like hexdump -C. As a result, these process substitutions do not
work when running a bytecode-compiled shell script.

The fix is surprisingly simple. A process substitution is encoded
as a complete parse tree. When used with a redirection, that parse
tree is used as the file name for the redirection. All we need to
do is treat the "file name" as a parse tree instead of a string if
flags indicate a process substitution.

A process substitution is detected by the struct ionod field
'iofile'. Checking the IOPROCSUB bit flag is not enough. We also
need to exclude the IOLSEEK flag as that form of redirection may
use the IOARITH flag which has the same bit value as IOPROCSUB (see
include/shnodes.h).

src/cmd/ksh93/sh/tdump.c: p_redirect():
- Call p_tree() instead of p_string() for a process substitution.

src/cmd/ksh93/sh/trestore.c: r_redirect():
- Call r_tree() instead of r_string() for a process substitution.

src/cmd/ksh93/include/version.h:
- Bump the shcomp binary header version as this change is not
  backwards compatible; previous trestore.c versions don't know how
  to read the newly compiled process substitutions and would crash.

src/cmd/ksh93/tests/io.sh:
- Add test.

src/cmd/ksh93/tests/builtins.sh,
src/cmd/ksh93/tests/options.sh:
- Revert shcomp workarounds. (re: 6701bb30)

Resolves: https://github.com/ksh93/ksh/issues/165

NEWS

@@ -3,6 +3,11 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2021-04-22:
+
+- shcomp (the shell bytecode compiler) was fixed to correctly compile process
+  substitutions used as the file name to a redirection, as in 'cmd < <(cmd)'.
+
 2021-04-21:
 
 - Fixed a bug introduced on 2020-09-28 that caused an interactive ksh to exit