git: fix i686 `wincred` build (take 2)
git: fix i686 `wincred` build (take 2)

Apparently, the CI agent's setup is significantly different from this
maintainer's, and therefore forcing `CC=gcc` was not enough. Let's use
the "cross" compiler for the desired CPU architecture directly.

Signed-off-by: Johannes Schindelin <53fb8db7833fca1e1746dd8592f61048d350f64c@gmx.de>

dscho/MINGW-packages,git-for-windows/MINGW-packages,dscho/MINGW-packages,git-for-windows/MINGW-packages,dscho/MINGW-packages,dscho/MINGW-packages,dscho/MINGW-packages,git-for-windows/MINGW-packages