package/mesa3d: drop r100 dependency on _HAS_ATOMIC

This partially reverts commit a3aac6d84713db7e6d2683eabf965eae21ce48bf,
just dropping the atomic dependency.

That dependency would introduce a "recursive dependency" chain in
Kconfig.

However, r100 is only available on i386 and x86-64, and they both have
sync4, which means libdrm's HAS_ATOMICS is always 'y' when r100 is
available.

So, like we did in 00c1a8c34f7 (package/mesa3d: propagate missing
libdrm-freedreno deps), we just add a fat comment that explains why the
dependency is not propagated.

Reported-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: James Hilliard <james.hilliard1@gmail.com>
Cc: Bernd Kuhls <bernd.kuhls@t-online.de>
(cherry picked from commit 0b029cac1bcacc957407e6437ffd371171f0607a)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mesa3d/Config.in

@@ -372,7 +372,11 @@ config BR2_PACKAGE_MESA3D_DRI_DRIVER_NOUVEAU
 config BR2_PACKAGE_MESA3D_DRI_DRIVER_RADEON
 	bool "DRI radeon r100 driver"
 	depends on BR2_i386 || BR2_x86_64
-	depends on BR2_PACKAGE_LIBDRM_HAS_ATOMIC
+	# libdrm's radeon option depends on LIBDRM_HAS_ATOMIC. Propagating
+	# that dependency here causes a circular dependency that Kconfig
+	# can't see is just spurious. However, that dependency is about
+	# the toolchain having sync4 primitives, which is always a given
+	# for i386 and x86_64.
 	select BR2_PACKAGE_MESA3D_DRI_DRIVER
 	select BR2_PACKAGE_LIBDRM_RADEON
 	help