Support arbitrary loggers.

While the defaults (logd or stderr) make sense for most use cases,
there are places that can only log to the kernel, or need to log to a
file, etc.

Allow the user to pass in an arbitrary logging object, and provide
LogdLogger and StderrLogger as defaults.

Change-Id: I62368acc795ff313242bb205d65017404bf64e88
diff --git a/base/logging_test.cpp b/base/logging_test.cpp
index 0a03e38..d947c1d 100644
--- a/base/logging_test.cpp
+++ b/base/logging_test.cpp
@@ -61,7 +61,7 @@
   int old_stderr_;
 };
 
-HOST_TEST(logging, CHECK) {
+TEST(logging, CHECK) {
   ASSERT_DEATH(CHECK(false), "Check failed: false ");
   CHECK(true);
 
@@ -82,7 +82,7 @@
       log_char, message);
 }
 
-HOST_TEST(logging, LOG) {
+TEST(logging, LOG) {
   ASSERT_DEATH(LOG(FATAL) << "foobar", "foobar");
 
   {
@@ -136,7 +136,7 @@
   }
 }
 
-HOST_TEST(logging, PLOG) {
+TEST(logging, PLOG) {
   {
     CapturedStderr cap;
     errno = ENOENT;
@@ -152,7 +152,7 @@
   }
 }
 
-HOST_TEST(logging, UNIMPLEMENTED) {
+TEST(logging, UNIMPLEMENTED) {
   {
     CapturedStderr cap;
     errno = ENOENT;