add portability test for gcc7.2
diff --git a/tools/run_tests/run_tests_matrix.py b/tools/run_tests/run_tests_matrix.py
index ae3a28b..433137a 100755
--- a/tools/run_tests/run_tests_matrix.py
+++ b/tools/run_tests/run_tests_matrix.py
@@ -260,7 +260,8 @@
 
     # portability C and C++ on x64
     for compiler in [
-            'gcc4.8', 'gcc5.3', 'gcc_musl', 'clang3.5', 'clang3.6', 'clang3.7'
+            'gcc4.8', 'gcc5.3', 'gcc7.2', 'gcc_musl', 'clang3.5', 'clang3.6',
+            'clang3.7'
     ]:
         test_jobs += _generate_jobs(
             languages=['c', 'c++'],