add missing operator=; fixes a crash that only occurs after releasing snapshots

stepmania/src/RageUtil.cpp

@@ -678,6 +678,7 @@ void Regex::Release()
 {
     delete (regex_t *)reg;
 	reg = NULL;
+	pattern = "";
 }
 
 Regex::Regex(const CString &str)
@@ -689,8 +690,13 @@ Regex::Regex(const CString &str)
 Regex::Regex(const Regex &rhs)
 {
 	reg = NULL;
-    pattern=rhs.pattern;
-	Compile();
+    Set(rhs.pattern);
+}
+
+Regex &Regex::operator=(const Regex &rhs)
+{
+	if(this != &rhs) Set(rhs.pattern);
+	return *this;
 }
 
 Regex::~Regex()

stepmania/src/RageUtil.h

@@ -209,6 +209,7 @@ class Regex {
 public:
 	Regex(const CString &pat = "");
 	Regex(const Regex &rhs);
+	Regex &operator=(const Regex &rhs);
 	~Regex();
 	void Set(const CString &str);
 	bool Compare(const CString &str);