[TableGen] emitStringLiteralDef: Pad trailing '\0' at the end of char array.

[chapuni]

Summary

Fixup for https://reviews.llvm.org/D73044
String literal has an implicit terminator '\0'. This commit adjusts char array
to long literal.

This causes difference of artifacts between -long-string-literals=true
and false.

[chapuni]

I will rebase this after D126135 will be applied.

[rnk]

lgtm

llvm/utils/TableGen/SequenceToOffsetTable.h

public:
   /// initializer, where each element is a C string literal terminated by
   /// `\0`. Falls back to emitting a comma-separated integer list if
   /// `EmitLongStrLiterals` is false
   void emitStringLiteralDef(raw_ostream &OS, const llvm::Twine &Decl) const {
     assert(Entries && "Call layout() before emitStringLiteralDef()");
     if (!EmitLongStrLiterals) {
       OS << Decl << " = {\n";
       emit(OS, printChar, "0");
-      OS << "\n};\n\n";
+      OS << "  0\n};\n\n";
       return;
     }
 
     OS << "\n#ifdef __GNUC__\n"
        << "#pragma GCC diagnostic push\n"
        << "#pragma GCC diagnostic ignored \"-Woverlength-strings\"\n"
        << "#endif\n"
        << Decl << " = {\n";