llvm-nm: print 'n' instead of '?'

This matches gnu nm and has the advantage that there is a upper case N.

llvm-svn: 240655

llvm/test/Object/X86/nm-print-size.s

@@ -1,7 +1,12 @@
 // RUN: llvm-mc %s -o %t -filetype=obj -triple=x86_64-pc-linux
 // RUN: llvm-nm --print-size %t | FileCheck %s
 
-// CHECK: 0000000000000000 ffffffffffffffff t a
+// CHECK: 0000000000000000 ffffffffffffffff n a
+// CHECK: 0000000000000000 0000000000000000 N b
 
+        .section foo
 a:
         .size a, 0xffffffffffffffff
+
+        .global b
+b:

llvm/tools/llvm-nm/llvm-nm.cpp

@@ -675,7 +675,7 @@ static char getSymbolNMTypeChar(ELFObjectFile<ELFT> &Obj,
         .Default('?');
   }
 
-  return '?';
+  return 'n';
 }
 
 static char getSymbolNMTypeChar(COFFObjectFile &Obj, symbol_iterator I) {