K2GO-446 fix(terminal): set a writable TMPDIR for the host shell

Running the iiab script via mksh surfaced a latent failure: mksh spools
here-docs to $TMPDIR, which is unset, so it fell back to a non-writable path and
the login here-doc failed ("can't create temporary file ...: Permission
denied"). Point TMPDIR at the app cache dir; the iiab function subshell inherits
it. Device-confirmed: iiab --login enters Debian with no temp-file error.

Author: luisguzman-adfa

controller/app/src/main/java/org/appdevforall/k2go/TerminalController.java

@@ -992,6 +992,9 @@ public void addNewSession() {
                     "TERM=xterm-256color",
                     "HOME=" + workingDirectory.getAbsolutePath(),
                     "ENV=" + mkshrcFile.getAbsolutePath(),
+                    // K2GO-446: writable TMPDIR so mksh can spool the iiab script's here-docs
+                    // (unset by default, mksh then falls back to a non-writable path).
+                    "TMPDIR=" + activity.getCacheDir().getAbsolutePath(),
                     // Include the system bins and our W^X fake prefix bins
                     "PATH=/sbin:/system/sbin:/system/bin:/system/xbin:" + workingDirectory.getAbsolutePath() + "/usr/bin"
             };