LSR: Calculate instruction cost only if InsnsCost is set to true (NFC)
The patch guard all instruction cost calculations with InsnCosts (-lsr-insns-cost) option.
Currently even if the option set to false we calculate and print (in debug mode) instruction costs.
Differential Revision: http://reviews.llvm.org/D33914
From: Evgeny Stupachenko <email@example.com>