Reapply "[dwarfdump] Add missing DW_LANG_Mips_Assembler case to LanguageString()"

This commit was reverted in r217183, but is OK to go in again now that its dependency is commited (as of r217186).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217231 91177308-0d34-0410-b5e6-96231b3b80d8
[dwarfdump] Dump DW_AT_(decl|call)_line attribute values as decimal values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217232 91177308-0d34-0410-b5e6-96231b3b80d8