Fix sanitizer choice for global vs module.
Fix sanitizer choice for global vs module.

The sanitizer chosen by the environment (either by SANITIZE_TARGET or
SANITIZE_HOST) should be chosen over the one specified by the module.

Bug: http://b/23330588
Change-Id: I835b7d76e071fc0db2f859f98dfb9d7ff76af245

xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build