Make javac always use Java 7 when running tests using javac and dx

This adds "-source 1.7 -target 1.7" to JAVAC when --build-with-javac-dx
is specified.

Also make sure that dx is not run when --jvm is passed.

Test: art/test/run-test --host --build-with-javac-dx 003-omnibus-opcodes
Test: art/test/run-test --host --build-with-javac-dx 005-annotations
Test: art/test/run-test --host --build-with-javac-dx 023-many-interfaces
Test: art/test/run-test --host --build-with-javac-dx 056-const-string-jumbo
Test: art/test/run-test --host --build-with-javac-dx 091-override-package-private-method
Test: art/test/run-test --host --build-with-javac-dx 111-unresolvable-exception
Test: art/test/run-test --host --build-with-javac-dx 113-multidex
Test: art/test/run-test --host --build-with-javac-dx 124-missing-classes
Test: art/test/run-test --host --build-with-javac-dx 126-miranda-multidex
Test: art/test/run-test --host --build-with-javac-dx 127-checker-secondarydex
Test: art/test/run-test --host --build-with-javac-dx 131-structural-change
Test: art/test/run-test --host --build-with-javac-dx 138-duplicate-classes-check2
Test: art/test/run-test --host --build-with-javac-dx 303-verification-stress
Test: art/test/run-test --host --build-with-javac-dx 551-checker-shifter-operand
Test: art/test/run-test --host --build-with-javac-dx 555-checker-regression-x86const

Test: art/test/run-test --host 003-omnibus-opcodes
Test: art/test/run-test --host 005-annotations
Test: art/test/run-test --host 023-many-interfaces
Test: art/test/run-test --host 056-const-string-jumbo
Test: art/test/run-test --host 091-override-package-private-method
Test: art/test/run-test --host 111-unresolvable-exception
Test: art/test/run-test --host 113-multidex
Test: art/test/run-test --host 124-missing-classes
Test: art/test/run-test --host 126-miranda-multidex
Test: art/test/run-test --host 127-checker-secondarydex
Test: art/test/run-test --host 131-structural-change
Test: art/test/run-test --host 138-duplicate-classes-check2
Test: art/test/run-test --host 303-verification-stress
Test: art/test/run-test --host 551-checker-shifter-operand
Test: art/test/run-test --host 555-checker-regression-x86const

Test: art/test/run-test --jvm 003-omnibus-opcodes
Test: art/test/run-test --jvm 005-annotations
Test: art/test/run-test --jvm 023-many-interfaces
Test: art/test/run-test --jvm 056-const-string-jumbo
Test: art/test/run-test --jvm 091-override-package-private-method
Test: art/test/run-test --jvm 111-unresolvable-exception
Test: art/test/run-test --jvm 113-multidex
Test: art/test/run-test --jvm 124-missing-classes
Test: art/test/run-test --jvm 126-miranda-multidex
Test: art/test/run-test --jvm 127-checker-secondarydex
Test: art/test/run-test --jvm 131-structural-change
Test: art/test/run-test --jvm 138-duplicate-classes-check2
Test: art/test/run-test --jvm 303-verification-stress
Test: art/test/run-test --jvm 551-checker-shifter-operand
Test: art/test/run-test --jvm 555-checker-regression-x86const

Change-Id: I60f8a973c0dd425988abe55223bdef426c772b97
diff --git a/test/run-test b/test/run-test
index 4c29420..10efe1f 100755
--- a/test/run-test
+++ b/test/run-test
@@ -540,6 +540,13 @@
     shift
 fi
 
+# For building with javac and dx always use Java 7. The dx compiler
+# only support byte codes from Java 7 or earlier (class file major
+# version 51 or lower).
+if [ "$USE_JACK" != "true" ] && [ "$NEED_DEX" = "true" ]; then
+  export JAVAC="${JAVAC} -source 1.7 -target 1.7"
+fi
+
 if [ "$usage" = "yes" ]; then
     prog=`basename $prog`
     (
@@ -561,8 +568,8 @@
         echo "    --gdb                 Run under gdb; incompatible with some tests."
         echo "    --gdb-arg             Pass an option to gdb."
         echo "    --build-only          Build test files only (off by default)."
-        echo "    --build-with-javac-dx Build test files with javac and dx (on by default)."
-        echo "    --build-with-jack     Build test files with jack and jill (off by default)."
+        echo "    --build-with-javac-dx Build test files with javac and dx (off by default)."
+        echo "    --build-with-jack     Build test files with jack and jill (on by default)."
         echo "    --interpreter         Enable interpreter only mode (off by default)."
         echo "    --jit                 Enable jit (off by default)."
         echo "    --optimizing          Enable optimizing compiler (default)."