Pin make target bouncycastle-bcpkix to java_version 1.7.

This decouples the class file version fed to jarjar from the
current default class file version.

Before this CL, it was using java_version 1.8 (the current
default). For consistency,

 - 1.7 was chosen for bouncycastle-bcpkix, consistent with
   other bouncycastle targets, and
 - its dependency, bouncycastle-bcpkix-nojarjar, was also
   pinned to 1.7, and
 - the target bouncycastle-ocsp-nojarjar is now explicitly
   pinned to 1.7 like its dependent target bouncycastle-ocsp.

Bug: 72703434
Test: EXPERIMENTAL_USE_OPENJDK9=true USE_R8=true make checkbuild docs
      (in a client where CL http://r.android.com/596874 was reverted)

Change-Id: I0c865a99f48335b2fa71db4f0f6938c577c50619
1 file changed