travis: add run with lua 5.1 without jit

Author: lonvia

.travis.yml

@@ -72,6 +72,18 @@ matrix:
            CXXFLAGS="-pedantic -Wextra -Werror"
            CC=gcc-5 CXX=g++-5 CPPVERSION=11
 
+    - os: linux
+      dist: bionic
+      compiler: gcc-7
+      env: T="bionic_gcc7_pg12"
+           PG_VERSIONS=12
+           POSTGIS_VERSION=3
+           LUA_VERSION=5.1
+           BUILD_TYPE="Debug" LUAJIT_OPTION="OFF"
+           CXXFLAGS="-pedantic -Wextra -Werror"
+           CC=gcc-7 CXX=g++-7 CPPVERSION=11
+
+
     - os: linux
       dist: bionic
       compiler: gcc-8