Dear all,

as correctly analyzed by Jerry, the code for checking the consistency
of character lengths in array constructors did not properly initialize
the auxiliary variable used in "bounds checking".  The attached patch
resolves this by initializing this auxiliary variable with a length
obtained by scanning the constructor.

Interestingly, the failure depended on optimization level and was
apparent only at -O0, and could exhibit both false-positives and
false-negatives.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Thanks,
Harald