Rename AtomicExpandLoadLinked into AtomicExpand

AtomicExpandLoadLinked is currently rather ARM-specific. This patch is the first of
a group that aim at making it more target-independent. See
http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-August/075873.html
for details

The command line option is "atomic-expand"

llvm-svn: 216231
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
index 9c4f052..25f2316 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.cpp
+++ b/llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -428,7 +428,7 @@
   return (!isThumb() || hasThumb2());
 }
 
-bool ARMSubtarget::enableAtomicExpandLoadLinked() const {
+bool ARMSubtarget::enableAtomicExpand() const {
   return hasAnyDataBarrier() && !isThumb1Only();
 }