README: update pre-requisites

- remove outdated deps
- add cmake

Change-Id: I5791f215aa26f9792cf20ba8593855484a887a51
Reviewed-on: https://weave-review.googlesource.com/3182
Reviewed-by: Paul Westbrook <pwestbro@google.com>

README.md

diff --git a/README.md b/README.md
index c179e61..bf04fea 100644
--- a/README.md
+++ b/README.md
@@ -58,14 +58,13 @@
   autoconf \
   automake \
   binutils \
+  cmake \
   g++ \
   hostapd \
   libavahi-client-dev \
   libcurl4-openssl-dev \
   libevent-dev \
   libexpat1-dev \
-  libnl-3-dev \
-  libnl-route-3-dev \
   libssl-dev \
   libtool
 ```
@@ -95,7 +94,6 @@
   - libevhtp (included; see third_party/libevhtp/)
   - libevent-dev
 
-
 # Compiling
 
 From the `libweave` directory:

examples/prerequisites.sh

diff --git a/examples/prerequisites.sh b/examples/prerequisites.sh
index 23d54d7..818fab6 100755
--- a/examples/prerequisites.sh
+++ b/examples/prerequisites.sh
@@ -20,8 +20,6 @@
   libcurl4-openssl-dev \
   libevent-dev \
   libexpat1-dev \
-  libnl-3-dev \
-  libnl-route-3-dev \
   libssl-dev \
   libtool \
   || exit 1