Grant additional permissions for ASAN builds

ASAN builds may require additional permissions to launch processes
with ASAN wrappers. In this case, system_server needs permission to
execute /system/bin/sh.

Create with_asan() macro which can be used exclusively on debug
builds. Note this means that ASAN builds with these additional
permission will not pass the security portion of CTS - like any
other debug build.

Addresses:
avc: denied { execute } for name="sh" dev="dm-0" ino=571
scontext=u:r:system_server:s0 tcontext=u:object_r:shell_exec:s0
tclass=file

Test: lunch aosp_marlin-userdebug;
      cd system/sepolicy; mm SANITIZE_TARGET=address;
      Verify permissions granted using with_asan() are granted.
Test: lunch aosp_marlin-userdebug;
      cd system/sepolicy; mm;
      Verify permissions granted using with_asan() are not granted.
Test: lunch aosp_marlin-user;
      cd system/sepolicy; mm SANITIZE_TARGET=address;
      Verify permissions granted using with_asan() are not granted.
Bug: 36138508
Change-Id: I6e39ada4bacd71687a593023f16b45bc16cd7ef8