fix boolean check for unknown rtconf variables in files.

BUG=

Review URL: https://codereview.chromium.org/15300019

git-svn-id: http://skia.googlecode.com/svn/trunk@9198 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/utils/SkRTConf.cpp b/src/utils/SkRTConf.cpp
index 29f0238..bc2031f 100644
--- a/src/utils/SkRTConf.cpp
+++ b/src/utils/SkRTConf.cpp
@@ -76,7 +76,7 @@
 // declared a correponding configuration object somewhere.
 void SkRTConfRegistry::validate() const {
     for (int i = 0 ; i < fConfigFileKeys.count() ; i++) {
-        if (fConfs.find(fConfigFileKeys[i]->c_str())) {
+        if (!fConfs.find(fConfigFileKeys[i]->c_str())) {
             SkDebugf("WARNING: You have config value %s in your configuration file, but I've never heard of that.\n", fConfigFileKeys[i]->c_str());
         }
     }