Install gdb 8 for CI:

A bug in gdb is crashing when demangling some symbols. Gdb needs to be updated
to at least gdb 8.

Only run the debug build under gdb (other builds can time out).

bin/ci/ubuntu/install-dependencies.sh

@@ -66,3 +66,16 @@ tar xfvz lcov-1.12.tar.gz -C $HOME
 # Set install path
 mkdir -p $LCOV_ROOT
 cd $HOME/lcov-1.12 && make install PREFIX=$LCOV_ROOT
+
+if [[ ${TARGET} == debug ]]; then
+    #install gdb
+    pushd $HOME
+    wget https://ftp.gnu.org/gnu/gdb/gdb-8.0.tar.xz
+    tar xf gdb-8.0.tar.xz
+    pushd gdb-8.0
+    ./configure CFLAGS='-w -O2' CXXFLAGS='-std=gnu++11 -g -O2 -w' --prefix=$GDB_ROOT
+    make -j2
+    make install
+    popd
+    popd
+fi