Don't use obsolete "org.apache.http.legacy.impl" in class loader context.

This library no longer exists on device and "org.apache.http.legacy"
should be used instead. The error lingered in the code for a while
because the code was not exercised at all. (The only app that sets
EnforceUsesLibraries is GoogleDialer (not in AOSP), and it specifies
"org.apache.http.legacy" explicitly as an optional used library.)

Test: lunch aosp_cf_x86_phone-userdebug && m
Change-Id: I05fa115476315d35a8877fc42bd1c2042f72f2de