libevhtp requires libevent-dev

So as to successfully build libevhtp, the prerequisites
script should include libevent-dev as well, else cmake
of libevhtp will complain

Change-Id: I627752e30c5f93f410e0d2f7415372dbe16052d2
Reviewed-on: https://weave-review.googlesource.com/2435
Reviewed-by: Jacob Marble <jacobmarble@google.com>

README.md

diff --git a/README.md b/README.md
index 6151061..fb8d092 100644
--- a/README.md
+++ b/README.md
@@ -87,8 +87,8 @@
   - hostapd
   - libavahi-client-dev
   - libcurl4-openssl-dev
-  - libevent 2.0.x
   - libevhtp (included; see third_party/get_libevhtp.sh)
+  - libevent-dev
 
 
 # Compiling

examples/prerequisites.sh

diff --git a/examples/prerequisites.sh b/examples/prerequisites.sh
index 4a019db..23d54d7 100755
--- a/examples/prerequisites.sh
+++ b/examples/prerequisites.sh
@@ -18,6 +18,7 @@
   hostapd \
   libavahi-client-dev \
   libcurl4-openssl-dev \
+  libevent-dev \
   libexpat1-dev \
   libnl-3-dev \
   libnl-route-3-dev \