Merge branch 'remove-bcc-support'

Remove support for Borland C++ compiler, it wasn't tested since a long
time and probably didn't work anyhow and there was no interest in
keeping support for it since many years.

See https://github.com/wxWidgets/wxWidgets/pull/2087

src/common/dcgraph.cpp

@@ -11,9 +11,6 @@
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
-#if defined(__BORLANDC__)
-    #pragma hdrstop
-#endif
 
 #if wxUSE_GRAPHICS_CONTEXT