[WebAssembly] Rename relocations from R_WEBASSEMBLY_ to R_WASM_

See https://github.com/WebAssembly/tool-conventions/pull/95.

This is less typing and IMHO more readable, and it also fits with
our naming around the binary format which tends to use the short name.
e.g.

include/llvm/BinaryFormat/Wasm.h
tools/llvm-objdump/WasmDump.cpp
etc..

Differential Revision: https://reviews.llvm.org/D57611

llvm-svn: 353062
diff --git a/llvm/test/tools/llvm-objdump/WebAssembly/relocations.test b/llvm/test/tools/llvm-objdump/WebAssembly/relocations.test
index 1384dd6..acf276e 100644
--- a/llvm/test/tools/llvm-objdump/WebAssembly/relocations.test
+++ b/llvm/test/tools/llvm-objdump/WebAssembly/relocations.test
@@ -10,7 +10,7 @@
 }
 
 ; CHECK:      RELOCATION RECORDS FOR [CODE]:
-; CHECK-NEXT: 00000006 R_WEBASSEMBLY_TYPE_INDEX_LEB 1+0
+; CHECK-NEXT: 00000006 R_WASM_TYPE_INDEX_LEB 1+0
 
 ; CHECK:      RELOCATION RECORDS FOR [DATA]:
-; CHECK-NEXT: 00000006 R_WEBASSEMBLY_MEMORY_ADDR_I32 foo+0
+; CHECK-NEXT: 00000006 R_WASM_MEMORY_ADDR_I32 foo+0