Cherry-pick "Refactor lazy JNI registration support."

> Rename the "linker_script_copy" target to "android_exports" and move the
> link_settings clause to that target. This avoids the linker flag being
> duplicated once for every target which includes jni_generator.gypi,
> which causes problems on some linker versions.
> BUG=402003
> Review URL:
> Cr-Commit-Position: refs/heads/master@{#289941}
> git-svn-id: svn:// 0039d316-1c4b-4281-b951-d872f2087c98

BUG: 16870075
Change-Id: Ic8a0906563edc777c3fc9a831643b8b535ede184
4 files changed