package/uclibc: backport patch to remove asm constraint on sparc

package/uclibc: backport patch to remove asm constraint on sparc

uClibc-ng don't build with gcc 9.1 [1] on sparc due to a new check
that "catch illegal asm constraint usage" [2]. This issue has been
fixed in upstream uclibc-ng, so we simply backport the fix.

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
[Thomas: backport the patch that was applied to upstream uclibc-ng]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>