[NFC][DebugInfo] Set a testing flag to be hidden

This flag (--try-experimental-debuginfo-iterators) only exists for testing
purposes, to get some RUNlines running in new-debug-info mode before it's
properly supported. The flag isn't something that's going to be useful to
people using llvm 18, so hide it from the options list.

Author: jmorse

llvm/tools/llc/llc.cpp

@@ -189,7 +189,7 @@ static cl::opt<std::string> RemarksFormat(
 static cl::opt<bool> TryUseNewDbgInfoFormat(
     "try-experimental-debuginfo-iterators",
     cl::desc("Enable debuginfo iterator positions, if they're built in"),
-    cl::init(false));
+    cl::init(false), cl::Hidden);
 
 extern cl::opt<bool> UseNewDbgInfoFormat;
 

llvm/tools/opt/opt.cpp

@@ -282,7 +282,7 @@ static cl::list<std::string>
 static cl::opt<bool> TryUseNewDbgInfoFormat(
     "try-experimental-debuginfo-iterators",
     cl::desc("Enable debuginfo iterator positions, if they're built in"),
-    cl::init(false));
+    cl::init(false), cl::Hidden);
 
 extern cl::opt<bool> UseNewDbgInfoFormat;