7zip reader: add test for POWERPC filter support for LZMA compressor (#2460)

7zip reader: add test for POWERPC filter support for LZMA compressor (#2460)

This new test archive contains a C hello world executable built like so
on a ubuntu 24.04 machine:
```
int main(int argc, char *argv[]) {
  printf("hello, world\n");
  return 0;
}
```

`powerpc-linux-gnu-gcc hw.c -o hw-powerpc -Wall`

The test archive that contains this executable was created like so,
using 7-Zip 24.08: `7zz a -t7z -m0=lzma2 -mf=ppc
libarchive/test/test_read_format_7zip_lzma2_powerpc.7z hw-powerpc`

The new test archive is required because the powerpc filter for lzma is
implemented in liblzma rather than in libarchive.