ndk: update JNIEXPORT declaration in <jni.h>

This patch updates the definition of JNIEXPORT in <jni.h> to
use the "default" ELF visibility attribute for JNI_OnLoad and
any function that uses the macro for its definition.

This is handy when a developer wants to use hidden visibility
by default by using a compiler flag like -fvisibility=hidden
in its Android.mk or custom build script.

Change-Id: I95112932731216a9a4986820a1875edfb3f52e5b
1 file changed