mpc: be0 conversion and update SRCURL

[niclas]

No description provided.

[wwwutz]

when removing we find a GCC dependency... WTF?!

> MISS libmpc.so.2                    /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/cc1
> MISS libmpc.so.2                    /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/cc1obj
> MISS libmpc.so.2                    /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/cc1objplus
> MISS libmpc.so.2                    /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/cc1plus
> MISS libmpc.so.2                    /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/f951
> MISS libmpc.so.2                    /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/lto1

lets dig in deeper ...

[wwwutz]

looks like something essential when building gcc

checking for the correct version of gmp.h... yes
checking for the correct version of mpfr.h... yes
checking for the correct version of mpc.h... yes
checking for the correct version of the gmp/mpfr/mpc libraries... yes

[wwwutz]

I personally would like to see a more... robust URL

[donald]

Current download: https://ftp.gnu.org/gnu/mpc/mpc-1.1.0.tar.gz which installs libmpc.so.3 so we should try a new package with 1.1.0 and a compat lib with libmpc.so.2.

[wwwutz]

added in #1605