DebugInfo: Update flag description that'd been copypasted from another

Post-commit review feedback from Paul Robinson on r309630. Thanks Paul!

llvm-svn: 309685
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 13c5203..b97ff4c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -63,7 +63,7 @@
 
 static cl::opt<bool> UseDwarfRangesBaseAddressSpecifier(
     "use-dwarf-ranges-base-address-specifier", cl::Hidden,
-    cl::desc("Disable debug info printing"), cl::init(false));
+    cl::desc("Use base address specifiers in debug_ranges"), cl::init(false));
 
 static cl::opt<bool>
     GenerateGnuPubSections("generate-gnu-dwarf-pub-sections", cl::Hidden,