Fix wrong comparison of uint[] due to invalid unsigned subtraction.
Add unittest for issue 13073.
Hmph, int[] comparison is also wrong (liable to int overflow).
Merge pull request #881 from quickfur/issue13073

Fix wrong comparison of uint[]/int[] due to invalid subtraction.
Fix 13111: GC.realloc returns invalid memory for large reallocation

added missing handling if the reallocation is too large for the current pool
add unittest
Fix marking threadasm.S as not requiring an executable stack.

- Use of @progbits breaks on ARM, use %progbits instead.
- Works on FreeBSD, too.
- Works only for ELF files.

See https://wiki.gentoo.org/wiki/Project:Hardened/GNU_stack_quickstart for more info.
Merge pull request #884 from rainers/fix_13111

Fix 13111: GC.realloc returns invalid memory for large reallocation
Merge pull request #885 from redstar/execstack

Fix marking threadasm.S as not requiring an executable stack.