Add a new method GetFunctionAddressAndSizeVector to DWARFCallFrameInfo.
This returns a vector of <file address, size> entries for all of
the functions in the module that have an eh_frame FDE.

Update ObjectFileMachO to use the eh_frame FDE function addresses if
the LC_FUNCTION_STARTS section is missing, to fill in the start
addresses of any symbols that have been stripped from the binary.

Generally speaking, lldb works best if it knows the actual start
address of every function in a module - it's especially important
for unwinding, where lldb inspects the instructions in the prologue
of the function.  In a stripped binary, it is deprived of this
information and it reduces the quality of our unwinds and saved
register retrieval.

Other ObjectFile users may want to use the function addresses from
DWARFCallFrameInfo to fill in any stripped symbols like ObjectFileMachO
does already.
<rdar://problem/13365659>