bootstrap: Set CXXFLAGS as well as CFLAGS in dev mode

Change-Id: I2fe0974182c2f207232b8e9b1f2d0acb7b57512c
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/bootstrap.sh b/bootstrap.sh
index 5f3d494..90a6951 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -30,9 +30,11 @@
 
 case "${BOOTSTRAP_MODE}" in
     dev)
+        FLAGS="-fsanitize=address -fsanitize=leak -fsanitize=undefined -Wall -Werror"
         ./configure \
             CPPFLAGS="-UNDEBUG" \
-            CFLAGS="-fsanitize=address -fsanitize=leak -fsanitize=undefined -Wall -Werror" \
+            CFLAGS="${FLAGS}" \
+            CXXFLAGS="${FLAGS}" \
             --enable-code-coverage \
             "$@"
         ;;