Switch NULL to C++11 nullptr in source/Interpreter

Patch by Robert Matusewicz

llvm-svn: 206711
diff --git a/lldb/source/Interpreter/OptionGroupFormat.cpp b/lldb/source/Interpreter/OptionGroupFormat.cpp
index 5cae378..f929b55 100644
--- a/lldb/source/Interpreter/OptionGroupFormat.cpp
+++ b/lldb/source/Interpreter/OptionGroupFormat.cpp
@@ -42,10 +42,10 @@
 static OptionDefinition 
 g_option_table[] =
 {
-{ LLDB_OPT_SET_1, false, "format"    ,'f', OptionParser::eRequiredArgument, NULL, 0, eArgTypeFormat   , "Specify a format to be used for display."},
-{ LLDB_OPT_SET_2, false, "gdb-format",'G', OptionParser::eRequiredArgument, NULL, 0, eArgTypeGDBFormat, "Specify a format using a GDB format specifier string."},
-{ LLDB_OPT_SET_3, false, "size"      ,'s', OptionParser::eRequiredArgument, NULL, 0, eArgTypeByteSize , "The size in bytes to use when displaying with the selected format."},
-{ LLDB_OPT_SET_4, false, "count"     ,'c', OptionParser::eRequiredArgument, NULL, 0, eArgTypeCount    , "The number of total items to display."},
+{ LLDB_OPT_SET_1, false, "format"    ,'f', OptionParser::eRequiredArgument, nullptr, 0, eArgTypeFormat   , "Specify a format to be used for display."},
+{ LLDB_OPT_SET_2, false, "gdb-format",'G', OptionParser::eRequiredArgument, nullptr, 0, eArgTypeGDBFormat, "Specify a format using a GDB format specifier string."},
+{ LLDB_OPT_SET_3, false, "size"      ,'s', OptionParser::eRequiredArgument, nullptr, 0, eArgTypeByteSize , "The size in bytes to use when displaying with the selected format."},
+{ LLDB_OPT_SET_4, false, "count"     ,'c', OptionParser::eRequiredArgument, nullptr, 0, eArgTypeCount    , "The number of total items to display."},
 };
 
 uint32_t
@@ -109,7 +109,7 @@
 
         case 'G':
             {
-                char *end = NULL;
+                char *end = nullptr;
                 const char *gdb_format_cstr = option_arg; 
                 uint64_t count = 0;
                 if (::isdigit (gdb_format_cstr[0]))