sb: Statically link zlib for GCC on MinGW

source-builder/config/gcc-common-1.cfg

@@ -119,6 +119,12 @@ BuildRoot: %{_tmppath}/%{name}-root-%(%{__id_u} -n)
   languages="$languages,objc"
 %endif
 
+%if %{_host_os} == mingw32
+  zlib_option=""
+%else
+  zlib_option="--with-system-zlib"
+%endif
+
   %{host_build_flags}
 
   ../${source_dir_gcc}/configure \
@@ -136,7 +142,7 @@ BuildRoot: %{_tmppath}/%{name}-root-%(%{__id_u} -n)
     --disable-libstdcxx-pch \
     --with-gnu-as --with-gnu-ld --verbose \
     --with-newlib \
-    --with-system-zlib \
+    "$zlib_option" \
     --disable-nls --without-included-gettext \
     --disable-win32-registry \
     --enable-version-specific-runtime-libs \