Go 1.10 was supposed to change the jclass JNI type to map to Go
uintptr, but failed to map the Android NDK definition until
recently.
There was a single instance in the reverse binding generator that
compared jclass values to nil. Change it to use 0 and cast the
jclass value to uintptr to ensure compatibility with older Go
releases.
Change-Id: Ifa22ed2db556220b7dfd0076b004bd8930219e08
Reviewed-on: https://go-review.googlesource.com/124915
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>