ci: update Travis configuration

 * Drop all versions of gcc < 7 and clang < 5
 * Add clang 11 (development branch)
 * Reenable ASan on Linux with clang 7, the upstream bug has been fixed
 * Drop Xcode 9.2 (macOS 10.12 is no longer supported)
 * Upgrade Xcode 11 to 11.3
 * Workaround issue with missing /usr/local/opt/openssl on macOS
 * Various cleanups

Change-Id: Iee54c0d0480b6ff15bb112a49b3a5c49586ac976
diff --git a/.jenkins.d/01-ndn-cxx.sh b/.jenkins.d/01-ndn-cxx.sh
index e627627..0ae5022 100755
--- a/.jenkins.d/01-ndn-cxx.sh
+++ b/.jenkins.d/01-ndn-cxx.sh
@@ -42,15 +42,13 @@
 
 pushd ndn-cxx >/dev/null
 
-./waf configure --color=yes --enable-shared --disable-static --without-osx-keychain
-./waf build --color=yes -j${WAF_JOBS:-1}
-sudo_preserve_env PATH -- ./waf install --color=yes
+./waf --color=yes configure --disable-static --enable-shared --without-osx-keychain
+./waf --color=yes build -j$WAF_JOBS
+sudo_preserve_env PATH -- ./waf --color=yes install
 
 popd >/dev/null
 popd >/dev/null
 
 if has Linux $NODE_LABELS; then
     sudo ldconfig
-elif has FreeBSD10 $NODE_LABELS; then
-    sudo ldconfig -m
 fi