Explicitly check for PropellerOptimizeInputFile being not null.
During fastbuild, PropellerOptimizeInputFile does not exist and this can cause
null pointer exception.  Explicitly check if this exists before accessing its
members.
@@ -248,6 +248,7 @@ public enum LinkBuildVariables {
}
if (featureConfiguration.isEnabled(CppRuleClasses.PROPELLER_OPTIMIZE)
+ && fdoContext.getPropellerOptimizeInputFile() != null
&& fdoContext.getPropellerOptimizeInputFile().getLdArtifact() != null) {
buildVariables.addStringVariable(
PROPELLER_OPTIMIZE_LD_PATH.getVariableName(),
