libatomic_ops: bump to version 7.6.6

Update COPYING hash: sync with FSF's gpl-2.0.txt (see
https://github.com/ivmai/libatomic_ops/commit/aed079e7ce21a033dd7ccb8fa5808d76e4ecb8d5)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libatomic_ops/libatomic_ops.hash

@@ -1,4 +1,4 @@
 # Locally calculated
-sha256 7ee6a1772a49d02711b97c600bd214bd86ba8a31bd7c6d6e850b502780de367c  libatomic_ops-v7.4.10.tar.gz
+sha256 61754aa60bb8052ea64175794df2afae8baacca5420e06eb150230681e71ff5e  libatomic_ops-v7.6.6.tar.gz
 sha256 f0e630c0ca489767033da5a0c869fb4231db522c5ff479ce55a853a923a00f69  doc/LICENSING.txt
-sha256 32b1062f7da84967e7019d01ab805935caa7ab7321a7ced0e30ebe75e5df1670  COPYING
+sha256 8177f97513213526df2cf6184d8ff986c675afb514d4e68a404010521b880643  COPYING

package/libatomic_ops/libatomic_ops.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-LIBATOMIC_OPS_VERSION = v7.4.10
+LIBATOMIC_OPS_VERSION = v7.6.6
 LIBATOMIC_OPS_SITE = $(call github,ivmai,libatomic_ops,$(LIBATOMIC_OPS_VERSION))
 LIBATOMIC_OPS_AUTORECONF = YES