Re-use ruby strings - #2

Re-use ruby strings

Handle integer overflow by treating number component as string if too large

fca9ae5 "avoid signed overflow" can still cause undefined behavior because
`compare_version_number` can return `INT_MIN` which `version_compare_cb_r`
then tries to negate:

```
../../../../ext/version_sorter/version_sorter.c:94:9: runtime error: negation of -2147483648 cannot be represented in type 'int'; cast to an unsigned type to negate this value to itself
    #0 0x7f9cde1fe1ba in version_compare_cb_r /tmp/x86_64-linux-gnu/version_sorter/2.3.1/../../../../ext/version_sorter/version_sorter.c:94:9
    #1 0x7f9cde75c231  (/lib/x86_64-linux-gnu/libc.so.6+0x39231)
    #2 0x7f9cde75c69e in qsort_r (/lib/x86_64-linux-gnu/libc.so.6+0x3969e)
    #3 0x7f9cde1fd68c in rb_version_sort_1 /tmp/x86_64-linux-gnu/version_sorter/2.3.1/../../../../ext/version_sorter/version_sorter.c:202:2
```