Refactor line.c to C++

src/openrct2/drawing/Line.cpp

@@ -16,6 +16,9 @@
 
 #include "drawing.h"
 
+extern "C"
+{
+
 /**
  * Draws a horizontal line of specified colour to a buffer.
  *  rct2: 0x0068474C
@@ -142,3 +145,5 @@ void gfx_draw_line_software(rct_drawpixelinfo *dpi, sint32 x1, sint32 y1, sint32
         }
     }
 }
+
+}