Use java variables from soong

Use TARGET_JAVAC and HOST_JAVAC exported from soong.

Test: m -j checkbuild
Merged-In: Ic094174149ea304c0b06ddc023417acf3602d5a3
Change-Id: Ic094174149ea304c0b06ddc023417acf3602d5a3
(cherry picked from commit 204dd14a2ca2483fd6da4d98dfc7a2910564c076)
1 file changed