openposix: Fix another three failures

This is a continuation of:

commit 38cc030
Author: Cyril Hrubis <[email protected]>
Date:   Thu Oct 29 15:16:30 2020 +0100

    openposix: Fix two test failures

Where I missed three more testcases that depended on variable being
changed from a different thread or signal handler.

Fixes: 8c22a59 (openposix: add "static" to all global variables and functions)
Signed-off-by: Cyril Hrubis <[email protected]>

Author: metan-ucw

testcases/open_posix_testsuite/conformance/interfaces/pthread_setschedparam/5-1.c

@@ -76,7 +76,7 @@
 /*****************************    Test case   *********************************/
 /******************************************************************************/
 
-static char do_it = 1;
+static volatile char do_it = 1;
 static unsigned long count_ope = 0;
 #ifdef WITH_SYNCHRO
 static sem_t semsig1;

testcases/open_posix_testsuite/conformance/interfaces/pthread_sigmask/18-1.c

@@ -75,7 +75,7 @@
 /***********************************    Test cases  *****************************************/
 /********************************************************************************************/
 
-static char do_it = 1;
+static volatile char do_it = 1;
 static unsigned long count_ope = 0;
 #ifdef WITH_SYNCHRO
 static sem_t semsig1;

testcases/open_posix_testsuite/conformance/interfaces/sem_unlink/9-1.c

@@ -82,7 +82,7 @@
 /******************************************************************************/
 /***************************    Test case   ***********************************/
 /******************************************************************************/
-static int thread_state = 0;
+static int volatile thread_state = 0;
 
 static void *threaded(void *arg)
 {