Try harder to save memory, add ix86 to 'save memory' list
    
    As per the other llvm packages, use ld flags that prioritize
    memory use over performance for memory-impaired arches. Also add
    ix86 to the list of memory-impaired arches, as my Rawhide build
    attempt died on i686 due to lack of memory:
    
    https://koji.fedoraproject.org/koji/taskinfo?taskID=25551155