Log Message:
Update www/libsass to 3.4.5.

Features
- Implement trailing commas in parameters and arguments
- Implement unary slash expressions

Fixes
- Fix Attribute Selector equal compare operator
- Fix segfault for varargs with non-string keys
- Fix Element Selector compare operators
- Fix compiler issue with spec regression on NetBSD 6.1
- Fix some segfaults caused by the parser being too forgiving
- Fix segfault with invalid map keys
- Fix null pointer dereference in css_error
- Fix bug when parsing selector schemas
- Fix null pointer dereference in parse_selector_schema
- Fix segfault when extending pseudo selectors failed
- Fix parser for urls looking like ruleset selectors
- Error for trailing rulesets comma
- Improve selector and binominal look ahead
- Improve hex escape handling in interpolation
- Fix wrong parsing of calc functions as number units
- Skip comment evaluation for compressed output
- Improve parent selector handling in selector schema
- Improve parameter vararg and keyword handling
- Hotfix to avoid invalid nested :not selectors
- Fix a few minor memory leaks