Fix to web assembly lib call list

Summary:
 Revision 307796 caused an internal build break in WebAssembly bots in the form of a
crash.  ex:
Here's the crash dump from one of the failing tests:

/usr/local/google/home/blaikie/dev/llvm/build/default/./bin/llc < /usr/local/google/home/blaikie/dev/llvm/src/test/CodeGen/WebAssembly/global.ll -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals | /usr/local/google/home/blaikie/dev/llvm/build/default/./bin/FileCheck /usr/local/google/home/blaikie/dev/llvm/src/test/CodeGen/WebAssembly/global.ll
--
Exit Code: 2

Command Output (stderr):
--
Stack dump:
0.      Program arguments: build/default/./bin/llc -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals
1.      Running pass 'Function Pass Manager' on module '<stdin>'.
2.      Running pass 'WebAssembly Assembly Printer' on function '@call_memcpy'
FileCheck error: '-' is empty.
FileCheck command line:  build/default/./bin/FileCheck src/test/CodeGen/WebAssembly/global.ll

The problem is in lib/Target/WebAssembly/WebAssemblyRuntimeLibcallSignatures.cpp. There’s an array declared:
545 static const char *
Fix to web assembly lib call list

Summary:
 Revision 307796 caused an internal build break in WebAssembly bots in the form of a
crash.  ex:
Here's the crash dump from one of the failing tests:

/usr/local/google/home/blaikie/dev/llvm/build/default/./bin/llc < /usr/local/google/home/blaikie/dev/llvm/src/test/CodeGen/WebAssembly/global.ll -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals | /usr/local/google/home/blaikie/dev/llvm/build/default/./bin/FileCheck /usr/local/google/home/blaikie/dev/llvm/src/test/CodeGen/WebAssembly/global.ll
--
Exit Code: 2

Command Output (stderr):
--
Stack dump:
0.      Program arguments: build/default/./bin/llc -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals
1.      Running pass 'Function Pass Manager' on module '<stdin>'.
2.      Running pass 'WebAssembly Assembly Printer' on function '@call_memcpy'
FileCheck error: '-' is empty.
FileCheck command line:  build/default/./bin/FileCheck src/test/CodeGen/WebAssembly/global.ll

The problem is in lib/Target/WebAssembly/WebAssemblyRuntimeLibcallSignatures.cpp. There’s an array declared:
static const char *
RuntimeLibcallNames[RTLIB::UNKNOWN_LIBCALL] = {

 That is defining a runtime lib call name for each entry in the enum RTLIB:Libcall from include/llvm/CodeGen/RuntimeLibcalls.h.

Revision 307796 added entries to the enum, but didn’t add entries to the RuntimeLibcallNames array, which caused a crash when attempting
to access past the end of the array.

This patch fixes the issue by adding the element atomic memmove to the WebAssembly arrays.

Reviewed by: reames

llvm-svn: 307831