include/

    include/
        * libiberty.h (PEX_STDERR_TO_PIPE): New define.
        (PEX_BINARY_ERROR): New define.
        (pex_read_err): New function.

        libiberty/
        * pex-common.h (struct pex_obj): New fields
        stderr_pipe and read_err.
        * pex-common.c (pex_init_common): Initialize
        stderr_pipe.
        (pex_run_in_environment): Add error checking
        for PEX_STDERR_TO_PIPE.  Create a pipe
        for stderr if necessary.
        (pex_read_err): New.
        (pex_free): Close read_err.
        * pexecute.txh: Document changes.
        * functions.texi: Regenerated.