mawk: fix passthru.tests, relax hardening options

`nix-build -A mawk.passthru.tests` was previously failing:
> error: builder for '/nix/store/gc20k2mizdw3aacda6nqwyvi7kqzn1dh-mawk-1.3.4-20240819-test-version.drv' failed with exit code 1;
>        last 2 log lines:
>        > mawk -W version returned a non-zero exit code.
>        > *** buffer overflow detected ***: terminated

the `mawk` binary was unusable; would crash on *any* invocation.

context: <https://github.com/NixOS/nixpkgs/pull/533402#issuecomment-4960077454>

pkgs/by-name/ma/mawk/package.nix

@@ -21,10 +21,15 @@ stdenv.mkDerivation (finalAttrs: {
 
   depsBuildBuild = [ buildPackages.stdenv.cc ];
 
+  hardeningDisable = [
+    "strictflexarrays1"
+  ];
+
   passthru = {
     tests.version = testers.testVersion {
       package = finalAttrs.finalPackage;
       command = "mawk -W version";
+      version = lib.replaceString "-" " " finalAttrs.version;
     };
     updateScript = directoryListingUpdater {
       inherit (finalAttrs) pname version;