[MIPS32] Fix mono_arch_get_cie_program and ELF_MACHINE undefined issue

[xiangzhai]

Hi,

Cross compile for MIPS32:

CC=mips-linux-gnu-gcc CFLAGS="-I./libatomic_ops/src" ./autogen.sh --host=mips-linux-gnu --prefix=/home/zhaixiang/mono-mips32-git
make
make install

And HelloWorld testcase PASSED for Loongson 3A3000:

$ ./mono-mips32-git/bin/mono HelloWorld/bin/Debug/netcoreapp3.0/HelloWorld.dll
Hello World!

Thanks,
Leslie Zhai

[xiangzhai]

Hi @vargaz

Thanks for your review!

Cheers,
Leslie Zhai

[vargaz]

@monojenkins build

[vargaz]

@monojenkins build failed