media: Fix MediaCodesXmlParser Result bug

In the constructor, we want to assign our new error string to
the struct member, instead of to the function argument.

Bug: 129710438
Test: TreeHugger
Change-Id: Id3a16fb048b3f5db97e455f6baaaec153b6bf6f0
diff --git a/media/libstagefright/xmlparser/MediaCodecsXmlParser.cpp b/media/libstagefright/xmlparser/MediaCodecsXmlParser.cpp
index 6a1b9a8..b1e5fbf 100644
--- a/media/libstagefright/xmlparser/MediaCodecsXmlParser.cpp
+++ b/media/libstagefright/xmlparser/MediaCodecsXmlParser.cpp
@@ -148,7 +148,7 @@
             : mStatus(s),
               mError(error) {
             if (error.empty() && s) {
-                error = "Failed (" + std::string(asString(s)) + ")";
+                mError = "Failed (" + std::string(asString(s)) + ")";
             }
         }
         operator status_t() const { return mStatus; }