Mips direct object exception handling regression

Revision 177141 caused a regression in all but
mips64 little endian. That is because none of the
other Mips targets had test cases checking the
contents of the .eh_frame section. This patch fixes
both the llvm code and adds an assembler test case
to include the current 4 flavors.

The test cases unfortunately rely on llvm-objdump. A
preferable method would be to use a pretty printer output
such as what readelf -wf <elf_file> would give.

I also changed the name of the test case to correct a typo.