Migrate SkRTConfRegistry test to DEF_TEST().

tests/RTConfRegistryTest.cpp

Index: tests/RTConfRegistryTest.cpp
diff --git a/tests/RTConfRegistryTest.cpp b/tests/RTConfRegistryTest.cpp
index f42281fa22f9bb75aa8e31aa3b5807b495b07556..59fb3e9142c81f8b1692738d1fdacac6bdda77ed 100644
--- a/tests/RTConfRegistryTest.cpp
+++ b/tests/RTConfRegistryTest.cpp
@@ -8,8 +8,25 @@
 #include "SkRTConf.h"
 #include "Test.h"
 
-DEF_TEST(SkRTConfRegistry, reporter) {
-#ifdef SK_SUPPORT_UNITTEST
-    SkRTConfRegistry::UnitTest();
+// Friended proxy for SkRTConfRegistry::parse()
+template <typename T>
+bool test_rt_conf_parse(SkRTConfRegistry* reg, const char* key, T* value) {
+    return reg->parse(key, value);
+}
+
+static void portable_setenv(const char* key, const char* value) {
+#ifdef SK_BUILD_FOR_WIN32
+    _putenv_s(key, value);
+#else
+    setenv(key, value, 1);
 #endif
 }
+
+DEF_TEST(SkRTConfRegistry, reporter) {
+    SkRTConfRegistry reg;
+
+    portable_setenv("skia_nonexistent_item", "132");
+    int result = 0;
+    test_rt_conf_parse(&reg, "nonexistent.item", &result);
+    REPORTER_ASSERT(reporter, result == 132);
+}