update: Add "UPDATE_DRYRUN" mode

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
mxe-conf.cmake: Workaround buggy windres rules

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
assimp: Update

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
assimp: Fix missing patch

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
assimp: Intentionally make the checksum wrong to test the server

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Revert "assimp: Intentionally make the checksum wrong to test the server"

This reverts commit e5add0b9442047bb40da910919b962e875fe33ec.

Fixes #531.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
libmikmod: Fix URL

Fixes part of #532.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
hdf4: Fix download URL

Fixes part of #532.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
gtkimageview: Fix download URL

Fixes part of #532.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
vigra: Fix download URL

Fixes remaining part of #532.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
vigra: Fix update macro

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
openssl: update