[DebugInfo] Accept `S` in augmentation strings in CIE.

glibc libc.a(sigaction.o) compiled from sysdeps/unix/sysv/linux/x86_64/sigaction.c uses "zRS".

llvm-svn: 331738

llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp

@@ -430,6 +430,9 @@ void DWARFDebugFrame::parse(DWARFDataExtractor Data) {
             case 'R':
               FDEPointerEncoding = Data.getU8(&Offset);
               break;
+            case 'S':
+              // Current frame is a signal trampoline.
+              break;
             case 'z':
               if (i)
                 ReportError(StartOffset,

llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp

@@ -565,7 +565,7 @@ int main(int argc, char **argv) {
     ShowChildren = true;
 
   // Defaults to a.out if no filenames specified.
-  if (InputFilenames.size() == 0)
+  if (InputFilenames.empty())
     InputFilenames.push_back("a.out");
 
   // Expand any .dSYM bundles to the individual object files contained therein.