Revert "yacas 1.3.6"

This reverts commit 6536705b8aab7b5c45ecc2973bf388a99aff6f80.
Revert 820fb42..0e7186f

This rolls back to commit 820fb42d9b4b787e5ba1729ed7ac8bb189d955de.
yacas 1.3.6

- corrected outdated keg
- added several lines of patches for successful build