Restore mingw64-x86_64-gcc-core to requirements for 32-bit builds in FAQ
listing required packages, and give reason.
<literal>perl</literal>, <literal>cocom</literal>, <literal>gettext-devel</literal>,
<literal>libiconv-devel</literal> and <literal>zlib-devel</literal>.
Building for 32-bit Cygwin also requires
+<literal>mingw64-x86_64-gcc-core</literal> (for building the cyglsa64 DLL for WoW64),
<literal>mingw64-i686-gcc-g++</literal> and <literal>mingw64-i686-zlib</literal>.
Building for 64-bit Cygwin also requires
<literal>mingw64-x86_64-gcc-g++</literal> and