[glibc/azanella/clang] Disable __USE_EXTERN_INLINES for clang

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=54e2ce20f29f8c0fb64ee5e0b6e7427109f955a3

commit 54e2ce20f29f8c0fb64ee5e0b6e7427109f955a3
Author: Fangrui Song <maskray@google.com>
Date:   Thu Oct 7 18:16:04 2021 -0700

    Disable __USE_EXTERN_INLINES for clang
    
    clang does not allow to redefine attributes after function declaration.
    Although it work for external usage, its breaks the build for internal
    symbol that glibc provides as optimization (for instance bsearch
    with stdlib-bsearch.h or __cmsg_nxthdr).
    
    Disable such optimization for clang while building glibc.

Diff:
---
 include/features.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/features.h b/include/features.h
index 26534f2b52..33eeb46a0a 100644
--- a/include/features.h
+++ b/include/features.h
@@ -503,7 +503,7 @@
 /* Decide whether we can define 'extern inline' functions in headers.  */
 #if __GNUC_PREREQ (2, 7) && defined __OPTIMIZE__ \
     && !defined __OPTIMIZE_SIZE__ && !defined __NO_INLINE__ \
-    && defined __extern_inline
+    && defined __extern_inline && !(defined __clang__ && defined _LIBC)
 # define __USE_EXTERN_INLINES	1
 #endif