build: require clang >= 3.6

Also fix an unused lambda capture warning with clang >= 5.0

Change-Id: I29c56cdf560da4a44efa038d4e65d868975aab6e
diff --git a/.travis.yml b/.travis.yml
index 984e8ac..2ac52ac 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -22,8 +22,6 @@
     # Linux/clang
     # https://apt.llvm.org/
     - os: linux
-      env: COMPILER=clang++-3.5
-    - os: linux
       env: COMPILER=clang++-3.6
     - os: linux
       env: COMPILER=clang++-3.7 DISABLE_ASAN=yes
@@ -46,25 +44,21 @@
       osx_image: xcode7.3
       env: OSX_VERSION=10.11
     - os: osx
+      osx_image: xcode8
+      env: OSX_VERSION=10.11
+    - os: osx
       osx_image: xcode8.3
       env: OSX_VERSION=10.12
     - os: osx
-      osx_image: xcode9.3
+      osx_image: xcode9.2
+      env: OSX_VERSION=10.12
+    - os: osx
+      osx_image: xcode9.4
       env: OSX_VERSION=10.13
 
   allow_failures:
-    - env: COMPILER=g++-6
-    - env: COMPILER=g++-7
-    - env: COMPILER=g++-8
-    - env: COMPILER=clang++-3.5
     - env: COMPILER=clang++-3.6
     - env: COMPILER=clang++-3.7 DISABLE_ASAN=yes
-    - env: COMPILER=clang++-3.8
-    - env: COMPILER=clang++-3.9
-    - env: COMPILER=clang++-4.0
-    - env: COMPILER=clang++-5.0
-    - env: COMPILER=clang++-6.0
-    - env: COMPILER=clang++-7
 
   fast_finish: true
 
diff --git a/.waf-tools/default-compiler-flags.py b/.waf-tools/default-compiler-flags.py
index e690290..2be9d90 100644
--- a/.waf-tools/default-compiler-flags.py
+++ b/.waf-tools/default-compiler-flags.py
@@ -20,9 +20,9 @@
                       'The minimum supported gcc version is 5.3.0.')
         conf.flags = GccFlags()
     elif cxx == 'clang':
-        if ccver < (3, 5, 0):
+        if ccver < (3, 6, 0):
             errmsg = ('The version of clang you are using is too old.\n'
-                      'The minimum supported clang version is 3.5.0.')
+                      'The minimum supported clang version is 3.6.0.')
         conf.flags = ClangFlags()
     else:
         warnmsg = 'Note: %s compiler is unsupported' % cxx
diff --git a/tests/tools/nfdc/face-module.t.cpp b/tests/tools/nfdc/face-module.t.cpp
index 994c0b2..a3f4618 100644
--- a/tests/tools/nfdc/face-module.t.cpp
+++ b/tests/tools/nfdc/face-module.t.cpp
@@ -478,8 +478,7 @@
 
 BOOST_AUTO_TEST_CASE(MtuExistingFace)
 {
-  bool hasUpdateCommand = false;
-  this->processInterest = [this, &hasUpdateCommand] (const Interest& interest) {
+  this->processInterest = [this] (const Interest& interest) {
     this->respond409(interest, FacePersistency::FACE_PERSISTENCY_ON_DEMAND, 4000);
     // no command other than faces/create is expected
   };