Some architectures do not have __sync_add_and_fetch_8 implemented.

MIPS (32-bit) and some PPC systems do not have sync_add_and_fetch_8.

Provide an alternative.  This alternative function is based on code from:
  https://github.com/mongodb/libbson/blob/master/src/bson/bson-atomic.c

Code is under an Apache 2.0 License.

Upstream-Status: Submitted [RPM5 maintainer]

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>

Index: rpm-5.4.15/rpmio/bson.h
===================================================================
--- rpm-5.4.15.orig/rpmio/bson.h
+++ rpm-5.4.15/rpmio/bson.h
@@ -879,10 +879,18 @@ BSON_END_DECLS
 
 BSON_BEGIN_DECLS
 
+/* Some architectures do not support __sync_add_and_fetch_8 */
+#if (__mips == 32) || (defined(__PPC__) && !defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8))
+# define __BSON_NEED_ATOMIC_64 1
+#endif
 
 #if defined(__GNUC__)
 # define bson_atomic_int_add(p, v)   (__sync_add_and_fetch(p, v))
-# define bson_atomic_int64_add(p, v) (__sync_add_and_fetch_8(p, v))
+#ifndef __BSON_NEED_ATOMIC_64
+#  define bson_atomic_int64_add(p, v) (__sync_add_and_fetch_8(p, v))
+# else
+   int64_t bson_atomic_int64_add (volatile int64_t *p, int64_t n);
+# endif
 # define bson_memory_barrier         __sync_synchronize
 #elif defined(_MSC_VER) || defined(_WIN32)
 # define bson_atomic_int_add(p, v)   (InterlockedExchangeAdd((long int *)(p), v))
Index: rpm-5.4.15/rpmio/bson.c
===================================================================
--- rpm-5.4.15.orig/rpmio/bson.c
+++ rpm-5.4.15/rpmio/bson.c
@@ -3863,13 +3863,30 @@ _bson_context_get_oid_seq64_threadsafe (
 #elif defined BSON_OS_WIN32
    uint64_t seq = InterlockedIncrement64 ((int64_t *)&context->seq64);
 #else
-   uint64_t seq = __sync_fetch_and_add_8 (&context->seq64, 1);
+   uint64_t seq = bson_atomic_int64_add (&context->seq64, 1);
 #endif
 
    seq = BSON_UINT64_TO_BE (seq);
    memcpy (&oid->bytes[4], &seq, 8);
 }
 
+#ifdef __BSON_NEED_ATOMIC_64
+#include <pthread.h>
+static pthread_mutex_t gSync64 = PTHREAD_MUTEX_INITIALIZER;
+int64_t
+bson_atomic_int64_add (volatile int64_t *p,
+                       int64_t           n)
+{
+   int64_t ret;
+
+   pthread_mutex_lock (&gSync64);
+   *p += n;
+   ret = *p;
+   pthread_mutex_unlock (&gSync64);
+
+   return ret;
+}
+#endif
 
 /**
  * bson_context_new: