Set default value for build_target's 'profiler' parameter to None

Test: pylint
Change-Id: I1901790fe33ef3d55facf4144ceadfb01b5d9ca7

test_compiler.py

diff --git a/test_compiler.py b/test_compiler.py
index 66f56ff..1f65527 100755
--- a/test_compiler.py
+++ b/test_compiler.py
@@ -190,7 +190,7 @@
 
 
 def build_target(android_base, clang_version, target, max_jobs, redirect_stderr,
-                 with_tidy, profiler):
+                 with_tidy, profiler=None):
     jobs = '-j{}'.format(max(1, min(max_jobs, multiprocessing.cpu_count())))
     env_out = subprocess.Popen(
         [