Starting with the 10.1 release, GCC defaults to -fno-common. This causes
linking issues when building genisoimage:
```bash
[ 98%] Building C object genisoimage/CMakeFiles/genisoimage.dir/checksum.o
[100%] Linking C executable genisoimage
/usr/bin/ld: CMakeFiles/genisoimage.dir/apple.o:(.bss+0x0): multiple definition of `outfile'; CMakeFiles/genisoimage.dir/genisoimage.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/genisoimage.dir/boot.o:(.bss+0x0): multiple definition of `outfile'; CMakeFiles/genisoimage.dir/genisoimage.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/genisoimage.dir/desktop.o:(.bss+0x0): multiple definition of `outfile'; CMakeFiles/genisoimage.dir/genisoimage.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/genisoimage.dir/dvd_file.o:(.bss+0x0): multiple definition of `outfile'; CMakeFiles/genisoimage.dir/genisoimage.o:(.bss+0x0): first defined here
```
Rather than patching genisoimage further, pass -fcommon to preserve the
legacy GCC behaviour.
Some dependency sources were downloaded via http, even though https (SSL/TLS) options are available.
Even if we potentially check the integrity of the downloaded files via hash comparison, we should make
use of this additional security layer.
bdb.mk
fontconfig.mk
freetype.mk
libX11.mk
libXau.mk
libXext.mk
libxcb.mk
native_cctools.mk
native_cdrkit.mk
xcb_proto.mk
xextproto.mk
xproto.mk
xtrans.mk
zlib.mk
miniupnp was switched to official project mirror with SSL support
