Fix bindep --brief for arch linux

Pacman output has changed and, as of v5.1.2, has a newline after
showing package x was not found.

Without this patch, the bindep --brief would throw an exception
because the stdout is not properly matched.

Change-Id: Ibe2ca0d426d6d8fa69b5c4ee9ccf0f6a07c862a7

bindep/depends.py

@@ -530,7 +530,7 @@ class Pacman(Platform):
                 stderr=subprocess.STDOUT).decode(getpreferredencoding(False))
         except subprocess.CalledProcessError as e:
             eoutput = e.output.decode(getpreferredencoding(False))
-            if e.returncode == 1 and eoutput.endswith('was not found'):
+            if e.returncode == 1 and eoutput.strip().endswith('was not found'):
                 return None
             raise
         # output looks like