travis: add CXXFLAGS=-Wnopsabi at ARM job

Author: ken2812221

.travis.yml

@@ -62,7 +62,9 @@ jobs:
         RUN_UNIT_TESTS=false
         RUN_FUNCTIONAL_TESTS=false
         GOAL="install"
-        BITCOIN_CONFIG="--enable-glibc-back-compat --enable-reduce-exports"
+        # -Wno-psabi is to disable ABI warnings: "note: parameter passing for argument of type ... changed in GCC 7.1"
+        # This could be removed once the ABI change warning does not show up by default
+        BITCOIN_CONFIG="--enable-glibc-back-compat --enable-reduce-exports CXXFLAGS=-Wno-psabi"
 # Win32
     - stage: test
       env: >-