Use llvm::stable_sort

While touching the code, simplify if feasible.

llvm-svn: 358996
diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
index 2994772..dab5bb3 100644
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -934,9 +934,8 @@
   // order, but for the code section we combine many MC sections into single
   // wasm section, and this order is determined by the order of Asm.Symbols()
   // not the sections order.
-  std::stable_sort(
-      Relocs.begin(), Relocs.end(),
-      [](const WasmRelocationEntry &A, const WasmRelocationEntry &B) {
+  llvm::stable_sort(
+      Relocs, [](const WasmRelocationEntry &A, const WasmRelocationEntry &B) {
         return (A.Offset + A.FixupSection->getSectionOffset()) <
                (B.Offset + B.FixupSection->getSectionOffset());
       });