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/build-and-test.sh

@@ -62,15 +62,19 @@ if [[ $TARGET == "coverage" ]]; then
   lcov --no-external -c -i -d . -o baseline.info
 fi
 
-# Execute unit tests under gdb, printing a call stack
-# if we get a crash.
-gdb -return-child-result -quiet -batch \
-    -ex "set env MALLOC_CHECK_=3" \
-    -ex "set print thread-events off" \
-    -ex run \
-    -ex "thread apply all backtrace full" \
-    -ex "quit" \
-    --args $APP_PATH $APP_ARGS
+if [[ ${TARGET} == debug ]]; then
+    # Execute unit tests under gdb, printing a call stack
+    # if we get a crash.
+    $GDB_ROOT/bin/gdb -return-child-result -quiet -batch \
+                      -ex "set env MALLOC_CHECK_=3" \
+                      -ex "set print thread-events off" \
+                      -ex run \
+                      -ex "thread apply all backtrace full" \
+                      -ex "quit" \
+                      --args $APP_PATH $APP_ARGS
+else
+    $APP_PATH $APP_ARGS
+fi
 
 if [[ $TARGET == "coverage" ]]; then
   # Create test coverage data file

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