Desugar when javac version is 1.7

Modules compiled with javac 1.7 may have LOCAL_STATIC_JAVA_LIBRARIES
pointing to jars that contain code compiled with javac 1.8, and may
need desugaring.

Test: m -j ANDROID_COMPILE_WITH_JACK=false checkbuild
Change-Id: I470fc0a2fba51179a3ef95986cb3030194cd8f1c
1 file changed