arch/Config.in.powerpc: disable some variants on ppc64le

Following commit
e59b3acc3603e55fbaec25406258ec9ca9623564 ("toolchain/glibc: Restrict
ppc64le support to power8"), when selecting ppc64le as the
architecture, it is possible to end up with a selection for which no C
library is provided.

Indeed:

 - glibc only supports Power8
 - uclibc has no support for ppc64le at all
 - musl only supports ppc64le processors that have Altivec support

Therefore, this commit adds "depends on !BR2_powerpc64le" to those
PowerPC architecture variants for which no C library support exists.

Fixes:

  http://autobuild.buildroot.net/results/3f6fb1c2d5648e78f7856bdea3171b5a89dfa2f9/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit c0b02883148025ea3e62535f237b246818155a99)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

arch/Config.in.powerpc

@@ -11,6 +11,8 @@ choice
 	  Specific CPU variant to use
 config BR2_generic_powerpc
 	bool "generic"
+	# No C library supports this variant on ppc64le
+	depends on !BR2_powerpc64le
 config BR2_powerpc_401
 	bool "401"
 	depends on !BR2_ARCH_IS_64
@@ -61,8 +63,12 @@ config BR2_powerpc_604e
 	depends on !BR2_ARCH_IS_64
 config BR2_powerpc_620
 	bool "620"
+	# No C library supports this variant on ppc64le
+	depends on !BR2_powerpc64le
 config BR2_powerpc_630
 	bool "630"
+	# No C library supports this variant on ppc64le
+	depends on !BR2_powerpc64le
 config BR2_powerpc_740
 	bool "740"
 	depends on !BR2_ARCH_IS_64
@@ -115,8 +121,12 @@ config BR2_powerpc_e6500
 	select BR2_POWERPC_CPU_HAS_ALTIVEC
 config BR2_powerpc_power4
 	bool "power4"
+	# No C library supports this variant on ppc64le
+	depends on !BR2_powerpc64le
 config BR2_powerpc_power5
 	bool "power5"
+	# No C library supports this variant on ppc64le
+	depends on !BR2_powerpc64le
 config BR2_powerpc_power6
 	bool "power6"
 	select BR2_POWERPC_CPU_HAS_ALTIVEC