[SRU Bionic+] LP#1770770 -- switch Build-Depends: from transfig to fig2dev

[Andy Whitcroft]

Some time back transfig became a transitional package to fig2dev.
In cosmic this transitional has now been deprecated.  As we are still
copying kernels forward we need to fix this dependency in bionic.
This transition actually occured back in artful, we just missed it.
Switch our build dependency to the "new" fig2dev package.

Following this email are patches for linux, linux-aws, linux-azure,
linux-gcp, linux-kvm, linux-oem, and linux-raspi2.

Proposing for SRU to bionic.

-apw