[gtkada] Build failure on gtkada 3.8.3

[Emmanuel Briot]

> Based upon the build of 3.8.2 the missing symbol 'sqrtf@@GLIBC_2.0' is
> resolved (on my host)  by appending (to the end of the link command) the
> library switch -lm

Gtkada (the development version at least) uses the output of

    pkg-config gtk+-3.0 --lilbs

to find out the list of libraries that are needed. On my machine, this includes -lm.

Your patch is complex, we will need time to review it. Thanks !

Emmanuel