Unblock signals after setting the handler

For safer execution, unblocking the signal after
setting the handler instead of before ensures all
signals get received by the correct handler.

Signed-off-by: Abdulrahman Alattas <rmnattas@gmail.com>

port/unix/omrsignal.c

@@ -1269,16 +1269,6 @@ registerSignalHandlerWithOS(OMRPortLibrary *portLibrary, uint32_t portLibrarySig
 		return OMRPORT_SIG_ERROR;
 	}
 
-	/* If a process has blocked a signal, then the signal stays blocked
-	 * in the sub-processes across fork(s) and exec(s). A blocked
-	 * signal prevents its OS signal handler to be invoked. A signal is
-	 * unblocked as an OS signal handler is installed for it in case a
-	 * parent process has blocked it.
-	 */
-	if (0 != unblockSignal(unixSignalNo)) {
-		return OMRPORT_SIG_ERROR;
-	}
-
 	memset(&newAction, 0, sizeof(struct sigaction));
 
 	/* Do not block any signals. */
@@ -1380,6 +1370,17 @@ registerSignalHandlerWithOS(OMRPortLibrary *portLibrary, uint32_t portLibrarySig
 		unsetBitMaskSignalsWithMainHandlers(portLibrarySignalNo);
 	}
 
+
+	/* If a process has blocked a signal, then the signal stays blocked
+	 * in the sub-processes across fork(s) and exec(s). A blocked
+	 * signal prevents its OS signal handler to be invoked. A signal is
+	 * unblocked as an OS signal handler is installed for it in case a
+	 * parent process has blocked it.
+	 */
+	if (0 != unblockSignal(unixSignalNo)) {
+		return OMRPORT_SIG_ERROR;
+	}
+
 	return 0;
 }