Fix a small regression impacting MSVC debug builds (#285)

* decomp: Fix nonempty_intersection impl for MSVC Debugging use-case

* docs: Add info on getting ASan builds running on Visual Studio w/o exceptions

decompiler/IR2/FormStack.cpp

@@ -110,10 +110,12 @@ Form* FormStack::pop_reg(const Variable& var,
 
 namespace {
 bool nonempty_intersection(const RegSet& a, const RegSet& b) {
-  // todo - if we ever switch to bit reg sets, this could be a lot faster.
-  std::vector<Register> isect;
-  std::set_intersection(a.begin(), a.end(), b.begin(), b.end(), std::back_inserter(isect));
-  return !isect.empty();
+  for (auto x : a) {
+    if (b.find(x) != b.end()) {
+      return true;
+    }
+  }
+  return false;
 }
 }  // namespace
 
@@ -378,4 +380,4 @@ std::vector<FormElement*> rewrite_to_get_var(FormStack& stack,
   return default_result;
 }
 
-}  // namespace decompiler
+}  // namespace decompiler