Add proguard rules for native referenced methods in matrix trace canary library

[littledog623]

There are some missing proguard rules for the trace canary library. Some Java class and method names are called from native c++ code, MatrixTracer.cc in specific. So we need to explicit keep those names in proguard, otherwise there will be errors like "java.lang.UnsatisfiedLinkError: JNI_ERR returned from JNI_OnLoad" at the host app side when loading the SO file.

[littledog623]

Can someone please review this :)