[patch] Fix segfault in vectorizer

[Eric Botcazou]

> I recall that some STMT_VINFO_RELEVANT_P checks have a ||
> STMT_VINFO_DEF_TYPE () == vect_reduction_def
> or VECTORIZABLE_CYCLE_DEF (STMT_VINFO_DEF_TYPE ()).  

It's rather || STMT_VINFO_LIVE_P in most cases and this works here, the 
vectorization is properly blocked:

opt56.adb:9:29: note: not vectorized: different sized masks types in 
statement, vector(16) unsigned char and vector(4) <unnamed type>
opt56.adb:9:29: note: can't determine vectorization factor.
opt56.adb:6:4: note: vectorized 0 loops in function.

-- 
Eric Botcazou