按照这些步骤https://gist.github.com/drewwells/ee5d42dc29b70b7b61af，可以成功安装mingw32。
我尝试使用brew brew install gcc48 --with-all-languages提供的gcc48作为brew公式再次执行此操作。
看来gcc-core需要使用mingw32头编译。这是错误输出：
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking _mingw_mac.h usability... no
checking _mingw_mac.h presence... no
checking for _mingw_mac.h... no
configure: error: Please check if the mingw-w64 header set and the build/host option are set properly.