tst_atomic: Add load, store and use __atomic builtins

Also add more fallback inline assembly for the existing architectures and add
SPARC64. Use the __atomic_* compiler intrinsics when available.

Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
diff --git a/configure.ac b/configure.ac
index 465655e..c84d3e4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -194,5 +194,6 @@
 LTP_CHECK_MMSGHDR
 LTP_CHECK_UNAME_DOMAINNAME
 LTP_CHECK_X_TABLES
+LTP_CHECK_ATOMIC_MEMORY_MODEL
 
 AC_OUTPUT