Remove the copyright comment from the outputs generated by RetDec.

It is a historical artifact from the times there was a decompilation service on
https://retdec.com. Now that RetDec is open-source, it makes little sense to
have the comment there. Even the usefulness of its presence in the past is
debatable.

Here is a quote from GPL FAQ [1], which I believe (but IANAL) applies to other
licenses as well:

> Q: Is there some way that I can GPL the output people get from use of my
> program? For example, if my program is used to develop hardware designs, can I
> require that these designs must be free?
>
> A: In general this is legally impossible; copyright law does not give you any
> say in the use of the output people make from their data using your program. If
> the user uses your program to enter or convert her own data, the copyright on
> the output belongs to her, not you. More generally, when a program translates
> its input into some other form, the copyright status of the output inherits
> that of the input it was generated from.

[1] https://www.gnu.org/licenses/gpl-faq.html#GPLOutput

src/bin2llvmir/optimizations/writer_dsm/writer_dsm.cpp

@@ -112,8 +112,6 @@ void DsmWriter::generateHeader(std::ostream& ret)
 	ret << ";;\n";
 	ret << ";; This file was generated by the Retargetable Decompiler\n";
 	ret << ";; Website: https://retdec.com\n";
-	ret << ";; Copyright (c) " << retdec::utils::getCurrentYear()
-	    << " Retargetable Decompiler <info@retdec.com>\n";
 	ret << ";;\n";
 	ret << ";; Decompilation date: "
 	    << retdec::utils::getCurrentDate() << " "

src/llvmir2hll/hll/hll_writer.cpp

@@ -359,12 +359,6 @@ bool HLLWriter::emitFileHeader() {
 	out->commentLine("");
 	out->commentLine("This file was generated by the Retargetable Decompiler");
 	out->commentLine("Website: https://retdec.com");
-	out->commentLine("Copyright (c)"
-		+ (optionEmitTimeVaryingInfo
-			? (" " + getCurrentYear())
-			: (""))
-		+ " Retargetable Decompiler <info@retdec.com>"
-	);
 	out->commentLine("");
 
 	return true;

tests/bin2llvmir/optimizations/writer_dsm/writer_dsm_tests.cpp

@@ -51,7 +51,6 @@ TEST_F(DsmWriterTests, testHeaderGeneration)
 R"(^;;
 ;; This file was generated by the Retargetable Decompiler
 ;; Website: https://retdec.com
-;; Copyright \(c\) 20.. Retargetable Decompiler <info@retdec.com>
 ;;
 ;; Decompilation date: ....-..-.. ..:..:..
 ;; Architecture: arm