Merge branch 'topic/gnatcheck/update_multiple_rule_files_test_case' into 'master'

Update the test case about having multiple "--rule-file" switches in the command-line

See merge request eng/libadalang/langkit-query-language!486

Author: thvnx

testsuite/tests/gnatcheck_errors/multiple_lkql_rule_files/main.adb

@@ -1,6 +1,6 @@
 procedure Main is
 begin
-   null;      --  FLAG
+   null;      --  NOFLAG
    goto lbl;  --  NOFLAG
    <<lbl>>
 end Main;

testsuite/tests/gnatcheck_errors/multiple_lkql_rule_files/test.out

@@ -1,35 +1,4 @@
-1. Summary
-
-   fully compliant sources               : 0
-   sources with exempted violations only : 0
-   sources with non-exempted violations  : 1
-   unverified sources                    : 0
-   total sources                         : 1
-   ignored sources                       : 0
-
-   non-exempted violations               : 1
-   rule exemption warnings               : 0
-   compilation errors                    : 0
-   exempted violations                   : 0
-   internal errors                       : 0
-
-2. Exempted Coding Standard Violations
-
-   no exempted violations detected
-
-3. Non-exempted Coding Standard Violations
-
-main.adb:3:04: rule violation: redundant null statement
-
-4. Rule exemption problems
-
-   no rule exemption problems detected
-
-5. Language violations
-
-   no language violations detected
-
-6. Gnatcheck internal errors
-
-   no internal error detected
-
+testsuite_driver: No output file generated by gnatcheck
+gnatcheck: error: invalid switch: --rule-file
+try "gnatcheck --help" for more information.
+>>>program returned status code 2