Switch the rest of our internal headers to #pragma once.

We've been using #pragma once for new internal files, but let's be more bold.

Bug: N/A
Test: builds
Change-Id: I7e2ee2730043bd884f9571cdbd8b524043030c07
diff --git a/linker/linker_logger.h b/linker/linker_logger.h
index 3e53f74..9ce438e 100644
--- a/linker/linker_logger.h
+++ b/linker/linker_logger.h
@@ -26,8 +26,7 @@
  * SUCH DAMAGE.
  */
 
-#ifndef _LINKER_LOGGER_H_
-#define _LINKER_LOGGER_H_
+#pragma once
 
 #include <stdlib.h>
 #include <limits.h>
@@ -61,5 +60,3 @@
 // If the system property debug.ld.greylist_disabled is true, we'll not use the greylist
 // regardless of API level.
 extern bool g_greylist_disabled;
-
-#endif /* _LINKER_LOGGER_H_ */