Install debug symbols for libc6 and odbc-postgresql

This should help with more informative stack traces in case of problems
such as ASAN reports.

scripts/travis/before_install.sh

@@ -6,7 +6,7 @@
 source ${TRAVIS_BUILD_DIR}/scripts/travis/common.sh
 
 sudo apt-get update -qq -y
-sudo apt-get install -qq -y libboost-dev libboost-date-time-dev
+sudo apt-get install -qq -y libc6-dbg libboost-dev libboost-date-time-dev
 
 before_install="${TRAVIS_BUILD_DIR}/scripts/travis/before_install_${SOCI_TRAVIS_BACKEND}.sh"
 if [ -x ${before_install} ]; then

scripts/travis/before_install_odbc.sh

@@ -8,4 +8,4 @@ source ${TRAVIS_BUILD_DIR}/scripts/travis/common.sh
 sudo apt-get install -qq \
     tar bzip2 \
     unixodbc-dev \
-    odbc-postgresql/xenial
+    odbc-postgresql/xenial odbc-postgresql-dbg/xenial