ci: update Travis-CI configuration

 * Re-enable ASan with gcc-7
 * Add clang-6.0 to the build matrix (allowed to fail)
 * Remove unsupported OSX-10.10 configuration
 * Upgrade xcode9 to xcode9.2
 * Add testing of openssl 1.1 on osx (allowed to fail)
 * Various simplifications

Change-Id: I3cdfcf78e6a9be66d1063fee710528698ad90bca
diff --git a/.jenkins.d/00-deps.sh b/.jenkins.d/00-deps.sh
index 66dafb4..79d65a2 100755
--- a/.jenkins.d/00-deps.sh
+++ b/.jenkins.d/00-deps.sh
@@ -7,7 +7,13 @@
 set -x
 
 if has OSX $NODE_LABELS; then
-    FORMULAE=(boost openssl pkg-config)
+    FORMULAE=(boost pkg-config)
+    if [[ -n $USE_OPENSSL_1_1 ]]; then
+        FORMULAE+=(openssl@1.1)
+    else
+        FORMULAE+=(openssl)
+    fi
+
     brew update
     if [[ -n $TRAVIS ]]; then
         # travis images come with a large number of brew packages