Optimize -36 bytes out of posix_memalign

And add a unit test

test/val/lib_common_pmemalign.c

@@ -0,0 +1,31 @@
+#include <errno.h>
+#include <stdlib.h>
+#include "unittest.h"
+
+TEST
+{
+    void *buf;
+    int r;
+
+    r = posix_memalign(&buf, 123, 1024);
+    ASSERT_IsTrue(r == EINVAL, "posix_memalign did not return EINVAL with wrong alignment");
+    ASSERT_IsTrue(buf == NULL, "posix_memalign did not set buf to NULL with wrong alignment");
+
+    r = posix_memalign(&buf, 0, 1024);
+    ASSERT_IsTrue(r == EINVAL, "posix_memalign did not return EINVAL with 0 alignment");
+    ASSERT_IsTrue(buf == NULL, "posix_memalign did not set buf to NULL with 0 alignment");
+
+    r = posix_memalign(&buf, 256, 0);
+    ASSERT_IsTrue(r == EINVAL, "posix_memalign did not return EINVAL with 0 size");
+    ASSERT_IsTrue(buf == NULL, "posix_memalign did not set buf to NULL with 0 size");
+
+    r = posix_memalign(&buf, 256, 32768U);
+    ASSERT_IsTrue(r == 0, "posix_memalign did not return 0 on correct call");
+    ASSERT_IsTrue(buf != NULL, "posix_memalign left buf set to NULL on correct call");
+    ASSERT_IsTrue(((unsigned int)buf & 0x00FF) == 0x00, "posix_memalign did not align memory");
+
+    r = posix_memalign(&buf, 256, 32768U);
+    ASSERT_IsTrue(r == ENOMEM, "posix_memalign did not return ENOMEM when no memory is available");
+    ASSERT_IsTrue(buf == NULL, "posix_memalign did not set buf to NULL when no memory is available");
+}
+ENDTEST