Make architecture names case insensitive.

Architecture names do not always come lower case. For example, IDA plugin does not do that: https://github.com/google/binexport/blob/a8572981126e455b99ba813edbc9a88a3269d8b6/ida/names.cc#L101

PiperOrigin-RevId: 691769928
Change-Id: I3014e85201cb6d66c7f8f17210bfc05f419100b7

Author: BinExport Authors

reader/flow_graph.cc

@@ -30,8 +30,8 @@ namespace security::binexport {
 namespace {
 
 absl::optional<Architecture> GetSupportedArchitecture(const BinExport2& proto) {
-  const std::string& architecture =
-      proto.meta_information().architecture_name();
+  const std::string architecture =
+      absl::AsciiStrToLower(proto.meta_information().architecture_name());
   if (architecture == "arm") {
     return Architecture::kArm;
   }