Provide Regex::exec backwards compatibility (#12549)

This tweaks #12546 to maintain ABI compatibility for the already
existing exec functions.

Author: bneradt

include/tsutil/Regex.h

@@ -125,20 +125,44 @@ class Regex
    *
    * It is safe to call this method concurrently on the same instance of @a this.
    */
-  bool exec(std::string_view subject, uint32_t flags = 0) const;
+  bool exec(std::string_view subject) const;
+
+  /** Execute the regular expression.
+   *
+   * @param subject String to match against.
+   * @param flags Match flags (e.g., RE_NOTEMPTY).
+   * @return @c true if the pattern matched, @a false if not.
+   *
+   * It is safe to call this method concurrently on the same instance of @a this.
+   */
+  bool exec(std::string_view subject, uint32_t flags) const;
+
+  /** Execute the regular expression.
+   *
+   * @param subject String to match against.
+   * @param matches Place to store the capture groups.
+   * @return @c The number of capture groups. < 0 if an error occurred. 0 if the number of Matches is too small.
+   *
+   * It is safe to call this method concurrently on the same instance of @a this.
+   *
+   * Each capture group takes 3 elements of @a ovector, therefore @a ovecsize must
+   * be a multiple of 3 and at least three times the number of desired capture groups.
+   */
+  int exec(std::string_view subject, RegexMatches &matches) const;
 
   /** Execute the regular expression.
    *
    * @param subject String to match against.
    * @param matches Place to store the capture groups.
+   * @param flags Match flags (e.g., RE_NOTEMPTY).
    * @return @c The number of capture groups. < 0 if an error occurred. 0 if the number of Matches is too small.
    *
    * It is safe to call this method concurrently on the same instance of @a this.
    *
    * Each capture group takes 3 elements of @a ovector, therefore @a ovecsize must
    * be a multiple of 3 and at least three times the number of desired capture groups.
    */
-  int exec(std::string_view subject, RegexMatches &matches, uint32_t flags = 0) const;
+  int exec(std::string_view subject, RegexMatches &matches, uint32_t flags) const;
 
   /// @return The number of capture groups in the compiled pattern.
   int get_capture_count();

src/tsutil/Regex.cc

@@ -295,6 +295,13 @@ Regex::compile(std::string_view pattern, std::string &error, int &erroroffset, u
   return true;
 }
 
+//----------------------------------------------------------------------------
+bool
+Regex::exec(std::string_view subject) const
+{
+  return this->exec(subject, 0);
+}
+
 //----------------------------------------------------------------------------
 bool
 Regex::exec(std::string_view subject, uint32_t flags) const
@@ -308,6 +315,13 @@ Regex::exec(std::string_view subject, uint32_t flags) const
   return count > 0;
 }
 
+//----------------------------------------------------------------------------
+int32_t
+Regex::exec(std::string_view subject, RegexMatches &matches) const
+{
+  return this->exec(subject, matches, 0);
+}
+
 //----------------------------------------------------------------------------
 int32_t
 Regex::exec(std::string_view subject, RegexMatches &matches, uint32_t flags) const