package/libbsd: needs an (e)glibc toolchain

libbsd needs support for .init_array and checks for a
glibc >= 2.4 since .init_array was introduced at around
that time.

uClibc claims to be a glibc-compatible toolchain, but it
only impersonates a glibc-2.2.

Just disable libbsd on uClibc.

Fixes:
    http://autobuild.buildroot.net/results/e94/e949d8fabeeecc74bd1c324c516e0b4938c99dbc/
    http://autobuild.buildroot.net/results/d3e/d3e1b70fb91571efacbe32af2cd12d055508f5ac/
    http://autobuild.buildroot.net/results/b19/b19d24dbf9d05d86d839349695da45d548705b25/
    [...]

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libbsd/Config.in

@@ -4,6 +4,7 @@ config BR2_PACKAGE_LIBBSD
 	# architectures: arm, m68k, x86 (and alpha, but we don't care.)
 	depends on ( BR2_i386 || BR2_x86_64 )
 	depends on BR2_TOOLCHAIN_HAS_THREADS
+	depends on BR2_TOOLCHAIN_USES_GLIBC
 	help
 	  This library provides useful functions commonly found on BSD
 	  systems, and lacking on others like GNU systems, thus making
@@ -13,6 +14,6 @@ config BR2_PACKAGE_LIBBSD
 
 	  http://libbsd.freedesktop.org/
 
-comment "libbsd needs a toolchain w/ threads"
+comment "libbsd needs an (e)glibc toolchain w/ threads"
 	depends on ( BR2_i386 || BR2_x86_64 )
-	depends on !BR2_TOOLCHAIN_HAS_THREADS
+	depends on !BR2_TOOLCHAIN_HAS_THREADS || !BR2_TOOLCHAIN_USES_GLIBC