regex_constants.h: Add underlying `unsigned int` for enum syntax_option_type.

2013-08-20  Tim Shen  <timshen91@gmail.com>

	* include/bits/regex_constants.h: Add underlying `unsigned int` for
	  enum syntax_option_type.

From-SVN: r201872

libstdc++-v3/ChangeLog

+2013-08-20  Tim Shen  <timshen91@gmail.com>
+
+	* include/bits/regex_constants.h: Add underlying `unsigned int` for
+	  enum syntax_option_type.
+
 2013-08-18  Tim Shen  <timshen91@gmail.com>
 
 	* include/bits/regex_automaton.h: _S_opcode_backref.

libstdc++-v3/include/bits/regex_constants.h

@@ -77,7 +77,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    * elements @c ECMAScript, @c basic, @c extended, @c awk, @c grep, @c egrep
    * %set.
    */
-  enum syntax_option_type
+  enum syntax_option_type : unsigned int
     {
       /**
        * Specifies that the matching of regular expressions against a character