busybox: fix ash segfaults after interrupting applet

[jmaksymowicz]

Backported fix from Busybox v1.36.

Description

If certain applets in ash are interrupted with ^C it could cause a corruption of the system state, which causes all subsequent commands to cause segfaults. This has been fixed in later versions of Busybox and this PR backports the fix.

Motivation and Context

Closes phoenix-rtos/phoenix-rtos-project#890

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

How Has This Been Tested?

• Already covered by automatic testing.
• New test added: (add PR link here).
• Tested by hand on: armv7a9-zynq7000-qemu, ia32-generic-qemu

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing linter checks and tests passed.
• My changes generate no new compilation warnings for any of the targets.

Special treatment

• This PR needs additional PRs to work (list the PRs, preferably in merge-order).
• I will merge this PR by myself when appropriate.

[github-actions]

Unit Test Results

6 410 tests  +408   5 780 ✅ +412   34m 15s ⏱️ + 4m 7s
  354 suites +  8     630 💤  -   4 
    1 files   ±  0       0 ❌ ±  0 

Results for commit e5900c5. ± Comparison against base commit 7a859f9.

♻️ This comment has been updated with latest results.