ci: update Travis configuration

 * Add testing on arm64, ppc64le, and s390x with select compiler versions
 * Allow disabling the headers check by setting DISABLE_HEADERS_CHECK
 * Drop all versions of gcc < 7 and clang < 5
 * Add clang 11 (development branch)
 * Reenable ASan on Linux with gcc 9 and clang 7, the upstream
   bugs have been fixed; ASan on clang 8 remains disabled
 * Drop Xcode 9.2 (macOS 10.12 is no longer supported)
 * Upgrade Xcode 11 to 11.3
 * Remove USE_OPENSSL_1_1 and always build with openssl 1.1.1,
   since that's the only version available on Homebrew now
 * Workaround issue with missing /usr/local/opt/openssl on macOS
 * Various cleanups

Change-Id: I90e7d61d176b60c1e6b90d2374a7a51dd1deabb3
diff --git a/.jenkins.d/00-deps.sh b/.jenkins.d/00-deps.sh
index ba85553..ae45ce5 100755
--- a/.jenkins.d/00-deps.sh
+++ b/.jenkins.d/00-deps.sh
@@ -7,13 +7,7 @@
 set -x
 
 if has OSX $NODE_LABELS; then
-    FORMULAE=(boost pkg-config)
-    if [[ -n $USE_OPENSSL_1_1 ]]; then
-        FORMULAE+=(openssl@1.1)
-    else
-        FORMULAE+=(openssl)
-    fi
-
+    FORMULAE=(boost openssl pkg-config)
     brew update
     if [[ -n $TRAVIS ]]; then
         # Travis images come with a large number of brew packages