Ticket #5907: Properly handle extern declarations in Tokenizer::simplifyVarDecl

Hi,

This patch teaches Tokenizer::simplifyVarDecl to properly grok extern variable declarations, which fixes the ticket, that was actually two-fold:
 1. Crash on the C++ variant
 2. Incorrect handling of the C variant, tokenizing it into "extern int * new , obj , player ;"

Thanks to consider merging.

Cheers,
  Simon