Revert "Revert "Update aosp/master libcxx rebase to r263688""

This reverts commit 1d4a1edbc7.

Change-Id: I2909937fe582f2c5552bc86e7f4d2d5cff0de0aa

include/complex.h

@@ -18,6 +18,12 @@
 
 */
 
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
 #ifdef __cplusplus
 
 #include <ccomplex>
@@ -28,8 +34,4 @@
 
 #endif  // __cplusplus
 
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#pragma GCC system_header
-#endif
-
 #endif  // _LIBCPP_COMPLEX_H