Work around wrong vsscanf() declaration under HP-UX.

Under this system vsscanf() is declared as taking a non-const char* as first
argument which prevented our code using it from compiling. Wrap it in
wxCRT_VsscanfA() adding the necessary const_cast<> to fix this.

Closes #15638.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75340 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

setup.h_vms

@@ -1107,6 +1107,10 @@ typedef pid_t GPid;
  * with 'char*' for the 3rd parameter instead of 'const char*' */
 #undef HAVE_BROKEN_VSNPRINTF_DECL
 
+/* Define if you have a _broken_ vsscanf() declaration in the header,
+ * with 'char*' for the 1st parameter instead of 'const char*' */
+#undef HAVE_BROKEN_VSSCANF_DECL
+
 /* Define if you have vsscanf() */
 #define HAVE_VSSCANF 1