Added support "__attribute__((__vector_size__(B)))" and "__attribute__((ext_vector_type(N)))". 

Now we can:
1 - see the return value for functions that return types that use the "ext_vector_size"
2 - dump values that use the vector attributes ("expr $ymm0")
3 - modified the DWARF parser to correctly parse GNU vector types from the DWARF by turning them into clang::Type::ExtVector types instead of just standard arrays



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@178924 91177308-0d34-0410-b5e6-96231b3b80d8