kvm tools: Add OPT_GROUP to cmdline parser

Add the OPT_GROUP parser option to allow the creation of an organized help menu.
Used code taken from the git project.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

include/kvm/parse-options.h

@@ -132,6 +132,12 @@ intptr_t defval;
 	.help = (h)                         \
 }
 
+#define OPT_GROUP(h)                        \
+{                                           \
+	.type = OPTION_GROUP,               \
+	.help = (h)                         \
+}
+
 #define OPT_END() { .type = OPTION_END }
 
 enum {