trinity: not available on musl

After fixing following build failures with musl:

* error: unknown type name __uint32_t and __uint64_t
* error: unknown type name pid_t and uid_t
* error: fatal error: bits/sockaddr.h: No such file or directory

it fails with

  fds/files.c: In function 'file_tree_callback':
  fds/files.c:172:10: error: 'FTW_CONTINUE' undeclared (first use in this function)
     return FTW_CONTINUE;
            ^
  fds/files.c:172:10: note: each undeclared identifier is reported only once for each function it appears in
  fds/files.c:178:10: error: 'FTW_SKIP_SUBTREE' undeclared (first use in this function)
     return FTW_SKIP_SUBTREE;
            ^
  fds/files.c:185:10: error: 'FTW_STOP' undeclared (first use in this function)
     return FTW_STOP;
            ^
  fds/files.c: In function 'open_fds_from_path':
  fds/files.c:197:26: error: 'FTW_ACTIONRETVAL' undeclared (first use in this function)
    int flags = FTW_DEPTH | FTW_ACTIONRETVAL | FTW_MOUNT;

As per ftw man-page, flag FTW_ACTIONRETVAL is specific to glibc. It is
not available on musl. Since package uses it unconditionally, we mark
it not available on musl.

Fixes:
  http://autobuild.buildroot.net/results/cb4/cb4a665746652679487dee2c2e4bca881be3724b/

Cc: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Rahul Bedarkar <rahul.bedarkar@imgtec.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/trinity/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_TRINITY
 	bool "trinity"
 	depends on BR2_USE_MMU # fork()
+	depends on !BR2_TOOLCHAIN_USES_MUSL # FTW_ACTIONRETVAL
 	depends on BR2_aarch64 || BR2_arm || BR2_armeb || BR2_i386 || \
 		BR2_mips || BR2_mipsel || BR2_powerpc || BR2_powerpc64 || \
 		BR2_powerpc64le || BR2_sparc || BR2_x86_64
@@ -8,3 +9,10 @@ config BR2_PACKAGE_TRINITY
 	  A Linux System call fuzz tester
 
 	  http://codemonkey.org.uk/projects/trinity/
+
+comment "trinity needs a uClibc or glibc toolchain"
+	depends on BR2_USE_MMU
+	depends on BR2_TOOLCHAIN_USES_MUSL
+	depends on BR2_aarch64 || BR2_arm || BR2_armeb || BR2_i386 || \
+		BR2_mips || BR2_mipsel || BR2_powerpc || BR2_powerpc64 || \
+		BR2_powerpc64le || BR2_sparc || BR2_x86_64