GTK interface fails to build as an internal port

Attempting to build the GTK interface as an internal
window port fails with the following error:

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gtk.o: In function `init_text_nhwindow':
gtk.o(.text+0x27ee): undefined reference to `md5_init'
gtk.o: In function `GTK_display_nhwindow':
gtk.o(.text+0x2c47): undefined reference to `md5_finish'
gtk.o: In function `GTK_putstr':
gtk.o(.text+0x31c4): undefined reference to
`md5_append'
gtkhackrc.o: In function `nh_write_gtkhackrc':
gtkhackrc.o(.text+0xf25): undefined reference to
`nh_help_save'
gtkhackrc.o: In function `rc_help_font':
gtkhackrc.o(.text+0x12d8): undefined reference to
`nh_set_help_font'