link-parser: On Panic parse, no need for sentence_parse() result
link-parser: On Panic parse, no need for sentence_parse() result

clang static analyzer:
Dead store	Dead assignment link-parser.c main	900	1

Remove the assinment.
Add '(void)" to signify that the result got neglected on purpose.

linas/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar,ampli/link-grammar,ampli/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,ampli/link-grammar,opencog/link-grammar,opencog/link-grammar,opencog/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar