Decode the common EM_ values.

We know what "3" and "40" are, but most folks not on our team don't.

I don't think we need to support all the weird values, because only the
supported architectures actually occur in practice.

Bug: N/A
Test: manually overwrote aarch64 libcrypto.so with an x86-64 .so and ran "date"
Test: CANNOT LINK EXECUTABLE "date": "/system/lib64/libcrypto.so" has unexpected e_machine: 62 (EM_X86_64)
Change-Id: Ic4c6325fe7968f0c96fc0bfe15a50ed922a5ba55