Fix comparison in if() check.
Fix comparison in if() check.

std::strstr() returns a char * or NULL if the substring
isn't found not false.

Signed-off-by: Koop Mast <a76d21fcfd54b15d6797326a99b3902d26c2dfa3@rainbow-runner.nl>
Reviewed-by: "Yang, Rong R" <78759e37dc7114caed18f74e7515c5cb519dbf6d@intel.com>

wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet