Fix ODR violations in code using <ext/atomicity.h>

Because the inline versions of __exchange_and_add and __atomic_add are
also marked static, they cannot be used from templates or other inline
functions without ODR violations. This change gives them external
linkage, but adds the always_inline attribute.

    	* include/ext/atomicity.h [_GLIBCXX_ATOMIC_BUILTINS] (__atomic_add)
    	(__exchange_and_add): Replace static specifier with always_inline
    	attribute.
    	(__exchange_and_add_single, __atomic_add_single): Likewise.
    	(__exchange_and_add_dispatch, __atomic_add_dispatch): Likewise. Also
    	combine !__gthread_active_p() and !__GTHREADS branches.

From-SVN: r273144

libstdc++-v3/ChangeLog

+2019-07-05  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/ext/atomicity.h [_GLIBCXX_ATOMIC_BUILTINS] (__atomic_add)
+	(__exchange_and_add): Replace static specifier with always_inline
+	attribute.
+	(__exchange_and_add_single, __atomic_add_single): Likewise.
+	(__exchange_and_add_dispatch, __atomic_add_dispatch): Likewise. Also
+	combine !__gthread_active_p() and !__GTHREADS branches.
+
 2019-07-03  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR libstdc++/91067

libstdc++-v3/include/ext/atomicity.h

@@ -44,24 +44,25 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // __exchange_and_add_dispatch
   // __atomic_add_dispatch
 #ifdef _GLIBCXX_ATOMIC_BUILTINS
-  static inline _Atomic_word 
+  inline _Atomic_word
+  __attribute__((__always_inline__))
   __exchange_and_add(volatile _Atomic_word* __mem, int __val)
   { return __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); }
 
-  static inline void
+  inline void
+  __attribute__((__always_inline__))
   __atomic_add(volatile _Atomic_word* __mem, int __val)
   { __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); }
 #else
   _Atomic_word
-  __attribute__ ((__unused__))
   __exchange_and_add(volatile _Atomic_word*, int) throw ();
 
   void
-  __attribute__ ((__unused__))
   __atomic_add(volatile _Atomic_word*, int) throw ();
 #endif
 
-  static inline _Atomic_word
+  inline _Atomic_word
+  __attribute__((__always_inline__))
   __exchange_and_add_single(_Atomic_word* __mem, int __val)
   {
     _Atomic_word __result = *__mem;
@@ -69,36 +70,31 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     return __result;
   }
 
-  static inline void
+  inline void
+  __attribute__((__always_inline__))
   __atomic_add_single(_Atomic_word* __mem, int __val)
   { *__mem += __val; }
 
-  static inline _Atomic_word
-  __attribute__ ((__unused__))
+  inline _Atomic_word
+  __attribute__ ((__always_inline__))
   __exchange_and_add_dispatch(_Atomic_word* __mem, int __val)
   {
 #ifdef __GTHREADS
     if (__gthread_active_p())
       return __exchange_and_add(__mem, __val);
-    else
-      return __exchange_and_add_single(__mem, __val);
-#else
-    return __exchange_and_add_single(__mem, __val);
 #endif
+    return __exchange_and_add_single(__mem, __val);
   }
 
-  static inline void
-  __attribute__ ((__unused__))
+  inline void
+  __attribute__ ((__always_inline__))
   __atomic_add_dispatch(_Atomic_word* __mem, int __val)
   {
 #ifdef __GTHREADS
     if (__gthread_active_p())
       __atomic_add(__mem, __val);
-    else
-      __atomic_add_single(__mem, __val);
-#else
-    __atomic_add_single(__mem, __val);
 #endif
+    __atomic_add_single(__mem, __val);
   }
 
 _GLIBCXX_END_NAMESPACE_VERSION