torture: Allow standalone kvm-recheck.sh run detect --trust-make

torture: Allow standalone kvm-recheck.sh run detect --trust-make

Normally, kvm-recheck.sh is run from kvm.sh, which provides the
TORTURE_TRUST_MAKE environment variable that, if a non-empty string,
indicates that the --trust-make command-line parameter has been passed
to kvm.sh.  If there was no --trust-make, kvm-recheck.sh insists
that the Make.out file contain at least one "CC" command.  Thus, when
kvm-recheck.sh is run standalone to evaluate a prior --trust-make run,
it will incorrectly insist that a proper kernel build did not happen.

This commit therefore causes kvm-recheck.sh to also search the "log"
file in the top-level results directory for the string "--trust-make".

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>