package/audit: not available for musl

audit uses strndupa() which is missing from musl.

Even though the implementation of strndupa is not too complex, we won't
go as far as duplicating it in audit, and we just disable audit for the
musl C library.

Fixes;
    http://autobuild.buildroot.org/results/e22/e22a70f9ff14bc52f642a6135da44c14e41b6cbb/
    http://autobuild.buildroot.org/results/233/2333c9b3d8f81b15602263b918d422e440f09d60/
    ...

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Clayton Shotwell <clayton.shotwell@rockwellcollins.com>
Cc: Matthew Weber <matthew.weber@rockwellcollins.com>
Cc: Ryan Barnett <rjbarnet@rockwellcollins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/audit/0001-Missed-cross-compile-fixes.patch

@@ -9,6 +9,7 @@ config BR2_PACKAGE_AUDIT
 	depends on BR2_PACKAGE_AUDIT_ARCH_SUPPORTS
 	depends on BR2_TOOLCHAIN_HAS_THREADS
 	depends on !BR2_STATIC_LIBS
+	depends on !BR2_TOOLCHAIN_USES_MUSL
 	help
 	  The audit package contains the user space utilities for
 	  storing and searching the audit records generated by
@@ -18,6 +19,7 @@ config BR2_PACKAGE_AUDIT
 
 	  http://people.redhat.com/sgrubb/audit/
 
-comment "audit needs a toolchain w/ threads, dynamic library"
-	depends on !BR2_TOOLCHAIN_HAS_THREADS || BR2_STATIC_LIBS
+comment "audit needs a uClibc or (e)glibc toolchain w/ threads, dynamic library"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS || BR2_STATIC_LIBS \
+		|| BR2_TOOLCHAIN_USES_MUSL
 	depends on BR2_PACKAGE_AUDIT_ARCH_SUPPORTS