Manpages of src:fltk1.3 in Debian unstable

• aarch64-linux-gnu-fltk-config(1)
• flblocks(6)
• flcheckers(6)
• flsudoku(6)
• fltk-config(1)
• fltk(3)
• fluid(1)
• riscv64-linux-gnu-fltk-config(1)
• x86_64-linux-gnu-fltk-config(1)