[MC] Remove unneeded zlib opt-out for .debug_frame

The opt-out from rL236267 (2015) is untested and seems no longer needed (or not
needed when rL236267 was committed): there is nothing special with uncompressed
alignment. This brings us in line with GCC which compresses .debug_frame .

Checked that -g -fno-asynchronous-unwind-tables + objcopy
--decompress-debug-sections output is identical to -g
-fno-asynchronous-unwind-tables -gz + objcopy --decompress-debug-sections
output.

llvm/lib/MC/ELFObjectWriter.cpp

@@ -848,13 +848,9 @@ void ELFWriter::writeSectionData(const MCAssembler &Asm, MCSection &Sec,
   auto &MC = Asm.getContext();
   const auto &MAI = MC.getAsmInfo();
 
-  // Compressing debug_frame requires handling alignment fragments which is
-  // more work (possibly generalizing MCAssembler.cpp:writeFragment to allow
-  // for writing to arbitrary buffers) for little benefit.
   bool CompressionEnabled =
       MAI->compressDebugSections() != DebugCompressionType::None;
-  if (!CompressionEnabled || !SectionName.startswith(".debug_") ||
-      SectionName == ".debug_frame") {
+  if (!CompressionEnabled || !SectionName.startswith(".debug_")) {
     Asm.writeSectionData(W.OS, &Section, Layout);
     return;
   }