package/crun: needs gcc >= 4.9

crun unconditionally uses atomic_bool when libgcrypt is found since
version 1.7.1 and
https://github.com/containers/crun/commit/40f66c0a74b8d918ecc7ae9228dca32a4fd71084
resulting in the following build failure with gcc 4.8 since commit
6987b92da510a8c8b9534a22506850c163d0f035:

src/libcrun/seccomp.c: In function 'calculate_seccomp_checksum':
src/libcrun/seccomp.c:374:3: error: unknown type name 'atomic_bool'
   static atomic_bool initialized = false;
   ^

Fixes:
 - http://autobuild.buildroot.org/results/924806ffd6d83cd6d8226577c3877b0b8ca2722d

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Christian Stewart <christian@paral.in>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/crun/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_CRUN
 	bool "crun"
 	depends on !BR2_TOOLCHAIN_USES_UCLIBC # no fexecve
+	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # C11/stdatomic.h
 	select BR2_PACKAGE_ARGP_STANDALONE if BR2_TOOLCHAIN_USES_MUSL
 	select BR2_PACKAGE_YAJL # libocispec
 	help
@@ -8,5 +9,6 @@ config BR2_PACKAGE_CRUN
 
 	  https://github.com/containers/crun
 
-comment "crun needs a glibc or musl toolchain"
-	depends on BR2_TOOLCHAIN_USES_UCLIBC
+comment "crun needs a glibc or musl toolchain, gcc >= 4.9"
+	depends on BR2_TOOLCHAIN_USES_UCLIBC || \
+		!BR2_TOOLCHAIN_GCC_AT_LEAST_4_9