Fix wxStyledTextCtrl compilation in non-Unicode build.

The value returned by wx2stc() in non-Unicode build is a simple "char*" and we
can't call length() method on it, add a helper wx2stclen() function to get the
length from the original wxString itself in this case.

Closes #14013.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71428 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/stc/private.h

@@ -23,6 +23,15 @@ extern wxString stc2wx(const char* str);
 extern wxString stc2wx(const char* str, size_t len);
 extern const wxWX2MBbuf wx2stc(const wxString& str);
 
+// This function takes both wxString and wxCharBuffer because it uses either
+// one or the other of them depending on the build mode. In Unicode it uses the
+// length of the already converted buffer to avoid doing the conversion again
+// just to compute the length.
+inline size_t wx2stclen(const wxString& WXUNUSED(str), const wxCharBuffer& buf)
+{
+    return buf.length() - 1;
+}
+
 #else // not UNICODE
 
 inline wxString stc2wx(const char* str) {
@@ -35,6 +44,12 @@ inline const wxWX2MBbuf wx2stc(const wxString& str) {
     return str.mbc_str();
 }
 
+// As explained above, the buffer argument is only used in Unicode build.
+inline size_t wx2stclen(const wxString& str, const char* WXUNUSED(buf))
+{
+    return str.length();
+}
+
 #endif // UNICODE
 
 #endif // _WX_STC_PRIVATE_H_