utest: test fork safety on OpenMP >= 5

In addition to testing fork safety on non-OpenMP builds, test it on
OpenMP >= 5.0, where we get the ability to release the locks at fork()
time.

Author: aitap

utest/Makefile

@@ -26,10 +26,7 @@ endif
 #this does not work with OpenMP nor with native Windows or Android threads
 # FIXME TBD if this works on OSX, SunOS, POWER and zarch
 ifeq ($(OSNAME), $(filter $(OSNAME),Linux CYGWIN_NT))
-ifneq ($(USE_OPENMP), 1)
-OBJS += test_fork.o
-endif
-OBJS += test_post_fork.o
+OBJS += test_fork.o test_post_fork.o
 endif
 
 ifeq ($(C_COMPILER), PGI)

utest/test_fork.c

@@ -64,7 +64,7 @@ static void check_dgemm(double *a, double *b, double *result, double *expected,
 
 CTEST(fork, safety)
 {
-#ifndef BUILD_DOUBLE
+#if !defined(BUILD_DOUBLE) || (defined(_OPENMP) && _OPENMP < 201811)
 exit(0);
 #else
     blasint n = 1000;