[Android] Fix v8_shell compilation for Android component build.

r12883 was in complete because the library was included for host and
target. Restrict to just target.

BUG=chromium:158821

Review URL: https://chromiumcodereview.appspot.com/12314118
Patch from Yaron Friedman <yfriedman@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13734 ce2b1a6d-e550-0410-aec6-3dcde31c8c00