extraParams -D lines make hxp misread libhxcpp's path #165

extraParams.hxml adds -D libhxcpp=<ver> and -D hxcpp=<ver> lines to haxelib path output. hxp, which Lime's tools use, takes the line before a library's -D <name> line as its path, so with the haxelib on the Lime build machine a dev install of libhxcpp resolved to -D libhxcpp=6.0.0. The compiler itself reads the lines correctly.

Set both defines with an init macro instead, so the only -D line is haxelib's own, right after the path.