Drop WX_NO_REGEX_ADVANCED and always define wxHAS_REGEX_ADVANCED

Using non-PCRE system regex library, which was the only build variant
when wxHAS_REGEX_ADVANCED was not defined, is not supported any more, so
simplify the code by not testing for it.

include/wx/features.h

@@ -53,13 +53,8 @@
     #undef wxHAS_CRASH_REPORT
 #endif
 
-/*  wxRE_ADVANCED is not always available, depending on regex library used
- *  (it's unavailable only if compiling via configure against system library) */
-#ifndef WX_NO_REGEX_ADVANCED
-    #define wxHAS_REGEX_ADVANCED
-#else
-    #undef wxHAS_REGEX_ADVANCED
-#endif
+/*  wxRE_ADVANCED is always defined now and kept for compatibility only. */
+#define wxHAS_REGEX_ADVANCED
 
 /* Pango-based ports and wxDFB use UTF-8 for text and font encodings
  * internally and so their fonts can handle any encodings: */

include/wx/osx/config_xcode.h

@@ -128,9 +128,6 @@
 #define PACKAGE_TARNAME "wxwidgets"
 #define PACKAGE_VERSION "3.1.6"
 
-// for regex
-#define WX_NO_REGEX_ADVANCED 1
-
 // for jpeg
 
 #define HAVE_STDLIB_H 1

include/wx/regex.h

@@ -27,10 +27,8 @@ enum
     // use extended regex syntax
     wxRE_EXTENDED = 0,
 
-    // use advanced RE syntax (built-in regex only)
-#ifdef wxHAS_REGEX_ADVANCED
+    // use advanced RE syntax (deprecated, same as wxRE_EXTENDED now)
     wxRE_ADVANCED = 1,
-#endif
 
     // use basic RE syntax
     wxRE_BASIC    = 2,