Add a better fix for searching for spaces in BSD archive object names where we...

Add a better fix for searching for spaces in BSD archive object names where we only trim trailing spaces.

I made an example where I had a file named "testtesttestt .o" (16 chars) that I was able to put into a .a file and we would previously truncate the object name to "testtesttestt" since we searched for any space in the name. I believe the BSD archive docs say that filenames with spaces will use the extended format, but our current libtool doesn't so I wanted to fix it by only removing trailing spaces.

llvm-svn: 244992