Make compiler-related gtests honor ART_USE_OPTIMIZING_COMPILER.

Previously, gtests using the art::CommonCompilerTest
class were using Quick as compiler.  Now, setting the
environment variable ART_USE_OPTIMIZING_COMPILER to `true`
before building and running these tests will use Optimizing
instead.

Change-Id: I724a3215d2eb1841089745fbabb5cb58b0422ef3
diff --git a/compiler/image_test.cc b/compiler/image_test.cc
index 772cc80..7e31a7a 100644
--- a/compiler/image_test.cc
+++ b/compiler/image_test.cc
@@ -45,6 +45,7 @@
 };
 
 TEST_F(ImageTest, WriteRead) {
+  TEST_DISABLED_FOR_NON_PIC_COMPILING_WITH_OPTIMIZING();
   // Create a generic location tmp file, to be the base of the .art and .oat temporary files.
   ScratchFile location;
   ScratchFile image_location(location, ".art");