Over this weekend I've performed scratch-mass-rebuild without having gcc and
gcc-c++ in buildroot of all Fedora packages, many of which failed due to random
reasons and I grepped all logs for some common errors found by analyzing
hundreds of build logs.

Guidelines: https://fedoraproject.org/wiki/Packaging:C_and_C%2B%2B#BuildRequire
s_and_Requies

The grep output is located here:
https://ignatenkobrain.fedorapeople.org/gcc-removal.txt

Some packages might be missed due to short koji outage, broken dependencies and
so on, but majority of real failures is below.

If you fixed package(s), found false positive, found missing packages in list
or anything else -- please let me know.

Note to packages which use CMake buildsystem. When you have project(xxx) in
CMakeLists.txt it checks both for C and CXX compilers. So you might encounter
packages where you have BuildRequires: gcc and it fails on CXX compiler (even
you think you don't need it). Solution for this is to send patch to upstream
switching to something like project(xxx C), or if problem is opposite to
project(xxx CXX).

List of packages and respective maintainers:
https://ignatenkobrain.fedorapeople.org/gcc-removal-pkgs.txt