tests: add osx test case for PIE builds.

test cases/osx/8 pie/main.c

@@ -0,0 +1,5 @@
+#include <CoreFoundation/CoreFoundation.h>
+
+int main(int argc, char **argv) {
+    return 0;
+}

test cases/osx/8 pie/meson.build

@@ -0,0 +1,3 @@
+project('osx pie', 'c')
+e = executable('prog', 'main.c', pie : true)
+test('pie', e)