Install gdb package in CI to make gdb_apit unit tests work

Author: danpoe

.travis.yml

@@ -99,6 +99,7 @@ jobs:
             - libubsan0
             - parallel
             - jq
+            - gdb
       before_install:
         - mkdir bin
         - ln -s /usr/bin/gcc-5 bin/gcc
@@ -134,6 +135,7 @@ jobs:
             - g++-5
             - libubsan0
             - jq
+            - gdb
       before_install:
         - mkdir bin
         - ln -s /usr/bin/gcc-5 bin/gcc
@@ -163,6 +165,7 @@ jobs:
             - libubsan0
             - parallel
             - jq
+            - gdb
       before_install:
         - mkdir bin
         - ln -s /usr/bin/gcc-5 bin/gcc
@@ -192,6 +195,7 @@ jobs:
             - libstdc++-5-dev
             - libubsan0
             - jq
+            - gdb
       before_install:
         - mkdir bin
         - ln -s /usr/bin/gcc-5 bin/gcc
@@ -219,6 +223,7 @@ jobs:
           packages:
             - g++-5
             - jq
+            - gdb
       before_install:
         - mkdir bin
         - ln -s /usr/bin/gcc-5 bin/gcc
@@ -246,6 +251,7 @@ jobs:
           packages:
             - g++-7
             - jq
+            - gdb
       before_install:
         - mkdir bin
         - ln -s /usr/bin/gcc-7 bin/gcc
@@ -279,6 +285,7 @@ jobs:
             - libubsan0
             - parallel
             - jq
+            - gdb
       before_install:
         - mkdir bin
         # Use gcc/g++ 5 for tests, as Clang doesn't work yet