[WebAssembly] Make __attribute__((used)) not imply export.

Add an WASM_SYMBOL_NO_STRIP flag, so that __attribute__((used)) doesn't
need to imply exporting. When targeting Emscripten, have
WASM_SYMBOL_NO_STRIP imply exporting.

Differential Revision: https://reviews.llvm.org/D62542


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@370415 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCWasmObjectTargetWriter.cpp

@@ -10,8 +10,9 @@
 
 using namespace llvm;
 
-MCWasmObjectTargetWriter::MCWasmObjectTargetWriter(bool Is64Bit)
-    : Is64Bit(Is64Bit) {}
+MCWasmObjectTargetWriter::MCWasmObjectTargetWriter(bool Is64Bit,
+                                                   bool IsEmscripten)
+    : Is64Bit(Is64Bit), IsEmscripten(IsEmscripten) {}
 
 // Pin the vtable to this object file
 MCWasmObjectTargetWriter::~MCWasmObjectTargetWriter() = default;