calc 2.17.0.2 release

Follow-up review fixes propagated stdout/stderr flush failures from
bounded block and string copies, reported string-buffer allocation
failures while collecting custom command output, corrected the custom
dependency recipe's stderr redirection, and added captured-output
regression coverage for both source types and standard streams.

This release follow-up addresses audit findings, adds output-bound
regression coverage, and bumps calc to 2.17.0.2.

Address review findings from the security audit follow-up, including
silent output truncation, missing regression coverage, inaccurate
release notes, and stale Makefile redirection.

• Error propagation

  • Return E_COPYF_3 when stdout/stderr flushes fail.
  • Propagate strext() allocation failures from custom command
    output capture.

  if (fflush(fp)) {
      return E_COPYF_3;
  }

• Regression coverage

  • Capture stdout and stderr for bounded block and string copies.
  • Verify exact output lengths for file IDs 1 and 2.

• Build and documentation

  • Replace stale /dev/null redirection in custom/Makefile.
  • Correct release-note tense and tty-state reallocation description.
  • Document all follow-up findings and fixes in CHANGES.

• Version

  • Bump calc from 2.17.0.1 to 2.17.0.2.

• Changes:

  • Propagates stream flush and output-buffer allocation failures.
  • Adds stdout/stderr bounded-copy regression tests.
  • Updates build redirection, release notes, and version metadata.
  • version.h: Bumps the compiled patch version.
  • Makefile.config: Updates the package version.
  • custom/u_pfe.c: Reports output-capture allocation failures.
  • custom/Makefile: Uses configurable stderr redirection.
  • CHANGES: Documents audit follow-up fixes.
  • cal/regress.cal: Tests bounded stdout/stderr copies.
  • blkcpy.c: Propagates standard-stream flush failures.

• Fixed Darwin regression error accounting and power saturation.

• Fixed test 9836 in cal/regress.cal.