perlPackages.XMLParser: Work around cross-compilation regression

Since 2.44_01, the behaviour for `check_lib` in their `Makefile.PL` has
been "fixed" to fail when the `assert_lib` function fails to build the
test.

 * https://github.com/toddr/XML-Parser/commit/2bc1e90c04220a04a0b40d1047d464bc55f56210

Now, this wouldn't be so bad, since it's good to actually test what
stuff is being compiled against.

Except that *something* is wonky with the cross-compilation build-time
Perl.

```
Undefined subroutine &File::Temp::mktemp called at inc/Devel/CheckLib.pm line 236.
```

As far as I know, this is a built-in function from Perl.

 * https://perldoc.perl.org/File/Temp.html

Though, something *else* is wrong with `Checklib.pm`. Side-stepping the
issue by (eww) shelling out to `mktemp`, we get these errors:

```

/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-armv7l-unknown-linux-gnueabihf-binutils-2.31.1/bin/armv7l-unknown-linux-gnueabihf-ld: assertlib_src1_0.553056903257133: file not recognized: file truncated
collect2: error: ld returned 1 exit status
 -I/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-expat-2.2.8-armv7l-unknown-linux-gnueabihf-dev/include -L/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-expat-2.2.8-armv7l-unknown-linux-gnueabihf/lib -lexpat
/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-armv7l-unknown-linux-gnueabihf-binutils-2.31.1/bin/armv7l-unknown-linux-gnueabihf-ld: assertlib_src2_0.262169388446154: file not recognized: file truncated
collect2: error: ld returned 1 exit status
Can't link/include C library 'expat.h', 'expat', aborting.
```

Meanwhile, the actual build, while building the library, seemingly has
no issues building using those paths. `¯\_(ツ)_/¯`