OS X: install pkg-config to build with FUSE support

Vagrantfile

@@ -72,7 +72,7 @@ def packages_darwin
     brew install xz  # required for python lzma module
     brew install fakeroot
     brew install git
-    brew install pkgconfig
+    brew install pkg-config
     touch ~vagrant/.bash_profile ; chown vagrant ~vagrant/.bash_profile
   EOF
 end

docs/installation.rst

@@ -228,6 +228,7 @@ Assuming you have installed homebrew_, the following steps will install all the
 dependencies::
 
     brew install python3 lz4 openssl
+    brew install pkg-config                            # optional, for FUSE support
     pip3 install virtualenv
 
 For FUSE support to mount the backup archives, you need at least version 3.0 of