Win: Add support for building the C++ dwtestoo with Visual C. Need to use dwmain() macro instead of standard main() entrypoint for Windows. Had to move the _dw_convertargs() definition outside of the dwmain() macro. The macro can be called from C++ code changing the function definition.

prefix=@prefix@
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${exec_prefix}/include
 
Name: dwindows
Description: Dynamic Windows Cross platform UI Toolkit
Version: @VERSION@
Libs: -L${prefix}/lib -ldwindows @LIBS@
Cflags: -I${prefix}/include @CFLAGS@ -D@DW_DEFINE@