stress-ng: disable DEBUG_BUILD

We get do_compile error when DEBUG_BUILD is enabled:

  error: inlining failed in call to 'always_inline' '_mm512_storeu_si512': target specific option mismatch

To reproduce the issue, set the following lines in local.conf
and then `bitbake stress-ng'.

  MACHINE = "qemux86-64"
  DEBUG_BUILD = "1"

A new issue is filed for stress-ng to track it:
https://github.com/ColinIanKing/stress-ng/issues/315

(From OE-Core rev: 3270f6f3bcb7811fd5e576808c086428f1a8c568)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-extended/stress-ng/stress-ng_0.16.04.bb

@@ -31,3 +31,6 @@ do_install() {
     oe_runmake DESTDIR=${D} BINDIR=${bindir} install
     ln -s stress-ng ${D}${bindir}/stress
 }
+
+# upstream issue: https://github.com/ColinIanKing/stress-ng/issues/315
+DEBUG_BUILD = "0"