Address librsvg header deprecation

[kench]

From #18, we have the following warnings in graphics/rsvg_frame.cpp:

g++ -g  -W -Wall -DRAWFRAME_POSIX_IO -D__STDC_CONSTANT_MACROS -fPIC -std=c++11  -DX86_64 -I/home/kenley/Downloads/bmdsdk/Linux/include  -pthread -I/usr/include/librsvg-2.0 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libpng12 -I/usr/include/cairo -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12 -I/usr/include/cairo -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12 -I/usr/include/freetype2 -I/usr/include/x86_64-linux-gnu -Iaudio/ -Imjpeg/ -Icommon/ -Iraw_frame/ -Ithread/ -Idrivers/ -Igraphics/ -Ireplay/ -Iavspipe/ -Ikeyer/ -Idisplay_surface/ -Iipc/  -c -o graphics/rsvg_frame.o graphics/rsvg_frame.cpp 
In file included from graphics/rsvg_frame.cpp:23:0:
/usr/include/librsvg-2.0/librsvg/rsvg-cairo.h:27:2: warning: #warning "Including <librsvg/rsvg-cairo.h> directly is deprecated." [-Wcpp]
 #warning "Including <librsvg/rsvg-cairo.h> directly is deprecated."
  ^
graphics/rsvg_frame.cpp: In function ‘void rsvg_tryinit()’:
graphics/rsvg_frame.cpp:57:9: warning: ‘void g_type_init()’ is deprecated [-Wdeprecated-declarations]
         g_type_init( );
         ^
In file included from /usr/include/glib-2.0/gobject/gobject.h:24:0,
                 from /usr/include/glib-2.0/gobject/gbinding.h:29,
                 from /usr/include/glib-2.0/glib-object.h:23,
                 from /usr/include/librsvg-2.0/librsvg/rsvg.h:31,
                 from graphics/rsvg_frame.cpp:22:
/usr/include/glib-2.0/gobject/gtype.h:681:23: note: declared here
 void                  g_type_init                    (void);
                       ^
graphics/rsvg_frame.cpp:57:9: warning: ‘void g_type_init()’ is deprecated [-Wdeprecated-declarations]
         g_type_init( );
         ^
In file included from /usr/include/glib-2.0/gobject/gobject.h:24:0,
                 from /usr/include/glib-2.0/gobject/gbinding.h:29,
                 from /usr/include/glib-2.0/glib-object.h:23,
                 from /usr/include/librsvg-2.0/librsvg/rsvg.h:31,
                 from graphics/rsvg_frame.cpp:22:
/usr/include/glib-2.0/gobject/gtype.h:681:23: note: declared here
 void                  g_type_init                    (void);
                       ^
graphics/rsvg_frame.cpp:57:22: warning: ‘void g_type_init()’ is deprecated [-Wdeprecated-declarations]
         g_type_init( );
                      ^
In file included from /usr/include/glib-2.0/gobject/gobject.h:24:0,
                 from /usr/include/glib-2.0/gobject/gbinding.h:29,
                 from /usr/include/glib-2.0/glib-object.h:23,
                 from /usr/include/librsvg-2.0/librsvg/rsvg.h:31,
                 from graphics/rsvg_frame.cpp:22:
/usr/include/glib-2.0/gobject/gtype.h:681:23: note: declared here
 void                  g_type_init                    (void);
                       ^
g++ -g  -W -Wall -DRAWFRAME_POSIX_IO -D__STDC_CONSTANT_MACROS -fPIC -std=c++11  -DX86_64 -I/home/kenley/Downloads/bmdsdk/Linux/include  -pthread -I/usr/include/librsvg-2.0 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libpng12 -I/usr/include/cairo -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12 -I/usr/include/cairo -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12 -I/usr/include/freetype2 -I/usr/include/x86_64-linux-gnu -Iaudio/ -Imjpeg/ -Icommon/ -Iraw_frame/ -Ithread/ -Idrivers/ -Igraphics/ -Ireplay/ -Iavspipe/ -Ikeyer/ -Idisplay_surface/ -Iipc/  -MM -MF graphics/freetype_font.o.d -MT graphics/freetype_font.o graphics/freetype_font.cpp

I feel like this is a small enough housekeeping task that I am able to pick up.