Make compiler/optimizing/ symbols hidden.

Make symbols in compiler/optimizing hidden by a namespace
attribute. The unit intrinsic_objects.{h,cc} is excluded as
it is needed by dex2oat.

As the symbols are no longer exported, gtests are now linked
with the static version of the libartd-compiler library.

libart-compiler.so size:
  - before:
    arm: 2396152
    arm64: 3345280
  - after:
    arm: 2016176 (-371KiB, -15.9%)
    arm64: 2874480 (-460KiB, -14.1%)

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing --jit
Bug: 142365358
Change-Id: I1fb04a33351f53f00b389a1642e81a68e40912a8
diff --git a/compiler/optimizing/intrinsics_utils.h b/compiler/optimizing/intrinsics_utils.h
index 41947f1..09d5fe6 100644
--- a/compiler/optimizing/intrinsics_utils.h
+++ b/compiler/optimizing/intrinsics_utils.h
@@ -24,7 +24,7 @@
 #include "utils/assembler.h"
 #include "utils/label.h"
 
-namespace art {
+namespace art HIDDEN {
 
 // Default slow-path for fallback (calling the managed code to handle the intrinsic) in an
 // intrinsified call. This will copy the arguments into the positions for a regular call.