[WebAssembly] Fix list of relocations with addends in lld

Summary:
The list of relocations with addend in lld was missing `R_WASM_MEMORY_ADDR_REL_SLEB`,
causing `wasm-ld` to generate corrupted output. This fixes that problem and while
we're at it pulls the list of such relocations into the Wasm.h header, to avoid
duplicating it in multiple places.

Reviewers: sbc100
Differential Revision: https://reviews.llvm.org/D63696

llvm-svn: 364367
diff --git a/llvm/lib/BinaryFormat/Wasm.cpp b/llvm/lib/BinaryFormat/Wasm.cpp
index 1d36b2c..d46be48 100644
--- a/llvm/lib/BinaryFormat/Wasm.cpp
+++ b/llvm/lib/BinaryFormat/Wasm.cpp
@@ -35,3 +35,17 @@
     llvm_unreachable("unknown reloc type");
   }
 }
+
+bool llvm::wasm::relocTypeHasAddend(uint32_t Type) {
+  switch (Type) {
+  case R_WASM_MEMORY_ADDR_LEB:
+  case R_WASM_MEMORY_ADDR_SLEB:
+  case R_WASM_MEMORY_ADDR_REL_SLEB:
+  case R_WASM_MEMORY_ADDR_I32:
+  case R_WASM_FUNCTION_OFFSET_I32:
+  case R_WASM_SECTION_OFFSET_I32:
+    return true;
+  default:
+    return false;
+  }
+}