Ok. It is working now!
So the linking of "libcryptopp.a" is not working on my Android project with "stlport" but only with "gnustl_static". Perhaps because of others include like "cocosd2-x".
So following the tuto "http://www.cryptopp.com/wiki/Android_(Command_Line)" you must change the script "setenv-android.sh" to have a result like this:
ANDROID_STL_INC: /Users/toto/Developer/NDKs/AndroidNDKs/android-ndk-r8e/sources/cxx-stl/gnu-libstdc++/4.6/include/
ANDROID_STL_LIB: /Users/toto/Developer/NDKs/AndroidNDKs/android-ndk-r8e/sources/cxx-stl/gnu-libstdc++/4.6/libs/armeabi/libgnustl_static.a
and also move the files (just for the compilation)
/Users/toto/Developer/NDKs/AndroidNDKs/android-ndk-r8e/sources/cxx-stl/gnu-libstdc++/4.6/libs/armeabi/include/bits
in
/Users/toto/Developer/NDKs/AndroidNDKs/android-ndk-r8e/sources/cxx-stl/gnu-libstdc++/4.6/include/bits
otherwise there are compilation problems...
Ouf!