Merge pull request #4599 from bruntib/cppcheck_unusedfunction_fix

[fix] Cppcheck suppress unusedFunction checker only once

Author: gulyasgergely902

analyzer/codechecker_analyzer/analyzers/cppcheck/analyzer.py

@@ -219,7 +219,8 @@ def construct_analyzer_cmd(self, result_handler):
 
             # unusedFunction check is for whole program analysis,
             # which is not compatible with per source file analysis.
-            analyzer_cmd.append('--suppress=unusedFunction')
+            if '--suppress=unusedFunction' not in analyzer_cmd:
+                analyzer_cmd.append('--suppress=unusedFunction')
 
             # Add extra arguments.
             analyzer_cmd.extend(config.analyzer_extra_arguments)