[gcc r11-11358] testsuite, objective-c++: Fix imported NSObjCRuntime.h.

[Iain D Sandoe <iains@gcc.gnu.org>]

https://gcc.gnu.org/g:c2a39d977605e554177236bf524c97ff14196f95

commit r11-11358-gc2a39d977605e554177236bf524c97ff14196f95
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Fri Jun 23 15:29:14 2023 +0100

    testsuite,objective-c++: Fix imported NSObjCRuntime.h.
    
    We have imported some headers from the GNUStep project to allow us
    to maintain the testsuite independent to changing versions of system
    headers.
    
    One of these headers has a macro that (now we have support for
    __has_feature) expands to a declaration that triggers a warning.
    
    These headers are considered part of the implementation so that, in
    this case, we can suppress the warning with the system_header pragma.
    
    Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
    
    gcc/testsuite/ChangeLog:
    
            * objc-obj-c++-shared/GNUStep/Foundation/NSObjCRuntime.h: Make
            this header use pragma system_header.
    
    (cherry picked from commit d83e0e3bc375a05844438d28c9a4ab24c5401eb9)

Diff:
---
 gcc/testsuite/objc-obj-c++-shared/GNUStep/Foundation/NSObjCRuntime.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gcc/testsuite/objc-obj-c++-shared/GNUStep/Foundation/NSObjCRuntime.h b/gcc/testsuite/objc-obj-c++-shared/GNUStep/Foundation/NSObjCRuntime.h
index 189af80436a..62556f9ac88 100644
--- a/gcc/testsuite/objc-obj-c++-shared/GNUStep/Foundation/NSObjCRuntime.h
+++ b/gcc/testsuite/objc-obj-c++-shared/GNUStep/Foundation/NSObjCRuntime.h
@@ -29,6 +29,9 @@
 #ifndef __NSObjCRuntime_h_GNUSTEP_BASE_INCLUDE
 #define __NSObjCRuntime_h_GNUSTEP_BASE_INCLUDE
 
+/* Allow the elaborated enum use in _GS_NAMED_ENUM. */
+#pragma GCC system_header
+
 #ifdef __cplusplus
 #ifndef __STDC_LIMIT_MACROS
 #define __STDC_LIMIT_MACROS 1