[llvm-symbolizer] Unhide and document the "-output-style" option

With the latest changes, the option gets useful for users of
llvm-symbolizer, not only for the upcoming llvm-addr2line.

Differential Revision: https://reviews.llvm.org/D60816

llvm-svn: 358748
diff --git a/llvm/tools/llvm-symbolizer/llvm-symbolizer.cpp b/llvm/tools/llvm-symbolizer/llvm-symbolizer.cpp
index c57f5f8..aa6635f 100644
--- a/llvm/tools/llvm-symbolizer/llvm-symbolizer.cpp
+++ b/llvm/tools/llvm-symbolizer/llvm-symbolizer.cpp
@@ -148,7 +148,7 @@
 
 static cl::opt<DIPrinter::OutputStyle>
     ClOutputStyle("output-style", cl::init(DIPrinter::OutputStyle::LLVM),
-                  cl::desc("Specify print style"), cl::Hidden,
+                  cl::desc("Specify print style"),
                   cl::values(clEnumValN(DIPrinter::OutputStyle::LLVM, "LLVM",
                                         "LLVM default style"),
                              clEnumValN(DIPrinter::OutputStyle::GNU, "GNU",