fix uninitialized memory error in mesh_build()
fix uninitialized memory error in mesh_build()

- manifested on 32 bit platforms

vlukes/sfepy,BubuLK/sfepy,rc/sfepy,RexFuzzle/sfepy,lokik/sfepy,sfepy/sfepy,lokik/sfepy,RexFuzzle/sfepy,RexFuzzle/sfepy,BubuLK/sfepy,vlukes/sfepy,BubuLK/sfepy,sfepy/sfepy,sfepy/sfepy,lokik/sfepy,vlukes/sfepy,RexFuzzle/sfepy,lokik/sfepy,rc/sfepy,rc/sfepy