ci : upgrade gradle to 2.4.2 (#1263)

* ci : upgrade gradle to 2.4.2

* cmake : add comment (#1129)

.github/workflows/build.yml

@@ -428,7 +428,7 @@ jobs:
 
       - name: Publish package
         if: ${{ github.ref == 'refs/heads/master' }}
-        uses: gradle/gradle-build-action@v2
+        uses: gradle/gradle-build-action@2.4.2
         with:
           arguments: publish
           build-root-directory: bindings/java

CMakeLists.txt

@@ -321,6 +321,10 @@ else()
     endif()
 endif()
 
+#
+# POSIX conformance
+#
+
 # clock_gettime came in POSIX.1b (1993)
 # CLOCK_MONOTONIC came in POSIX.1-2001 / SUSv3 as optional
 # posix_memalign came in POSIX.1-2001 / SUSv3