Add nacl_loader_unittests to the chromium_builder_tests

Now nacl_loader target is built on all platforms. Also,
nacl_loader target was renamed to nacl_linux.

TEST=ninja -C out/Release chromium_builder_tests
TEST=GYP_DEFINES='disable_nacl=1' ./build/gyp_chromium \
     ninja -C out/Release chromium_builder_tests
TEST=trybots
BUG=364751
R=mseaborn@chromium.org

Review URL: https://codereview.chromium.org/260063002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@266769 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

all.gyp

@@ -385,6 +385,11 @@
             '../ash/ash.gyp:ash_unittests',
           ],
         }],
+        ['disable_nacl==0', {
+          'dependencies': [
+            '../components/nacl.gyp:nacl_loader_unittests',
+          ],
+        }],
       ],
     }, # target_name: chromium_builder_tests
     {