update to more recent version of Android class library

Lots has changed since we forked Android's libcore, so merging the
latest upstream code has required extensive changes to the
Avian/Android port.

One big change is that we now use Avian's versions of
java.lang.Object, java.lang.Class, java.lang.ClassLoader, some
java.lang.reflect.* classes, etc. instead of the Android versions.
The main reason is that the Android versions have become very
Dex/Dalvik-specific, and since Avian is based on Java class files, not
dex archives, that code doesn't make sense here.  This has the side
benefit that we can share more native code with classpath-avian.cpp
and reduce the amount of Java/C++ code duplication.
fix SSL stack and Android JAR resource loading
fix Android thread enumeration
Small fix for Android Classpath on MacOS
Fixed jar tool usage - we should call "$(jar)" instead of simply "jar"
Fixed missing __BEGIN_DECLS / __END_DECLS on MinGW
Fixed CFLAGS for Android classpath under MinGW
Makefile fix for new ICU4C on Windows
a couple of tweaks to get Mac/Android tests passing
add Avian_java_lang_Thread_nativeSetName stub
update README.md to reflect conscrypt fork
Merge remote-tracking branch 'origin/master' into android-upgrade
provide slightly more complete Thread.nativeGetStatus implementation

This fixes SimpleFramework (which depends on Thread.getState returning
Thread.State.NEW for unstarted threads) when using the Android class
library.
Merge remote-tracking branch 'origin/master' into android-upgrade
Merge remote-tracking branch 'dicej/android-upgrade' into android-upgrade
Added isAnonymousClass(), isLocalClass(), isMemberClass() functions to Class class
Added getGenericInterfaces() and fixed SignatureParser to work for everything except TypeVariable-s
fix Class.getInterfaces to return only declared interfaces

Previously, we returned all interfaces implemented directly or
indirectly, which did not match the JDK behavior.
Merge pull request #345 from dicej/class-getinterfaces

fix Class.getInterfaces to return only declared interfaces
add detection for iOS 8 SDK