system/Config.in: disable openrc with uclibc

openrc raises the following uclibc build failures since bump to version
0.51 in commit 730c90faa3ec13ee1ead47113c9c5c7d3a8dac55:

../src/rc-abort/rc-abort.c: In function 'main':
../src/rc-abort/rc-abort.c:27:21: error: implicit declaration of function 'kill'; did you mean 'killpg'? [-Werror=implicit-function-declaration]
   27 |                 if (kill(pid, SIGUSR1) != 0)
      |                     ^~~~
      |                     killpg

../src/libeinfo/libeinfo.c: In function 'colour_terminal':
../src/libeinfo/libeinfo.c:319:26: error: implicit declaration of function 'fileno' [-Werror=implicit-function-declaration]
  319 |         if (f && !isatty(fileno(f)))
      |                          ^~~~~~

../src/librc/librc-misc.c: In function 'rc_getfile':
../src/librc/librc-misc.c:79:14: error: implicit declaration of function 'fileno'; did you mean 'd_fileno'? [-Werror=implicit-function-declaration]
   79 |         fd = fileno(fp);
      |              ^~~~~~
      |              d_fileno

../src/librc/librc-daemon.c: In function 'rc_service_daemons_crashed':
../src/librc/librc-daemon.c:633:37: error: implicit declaration of function 'kill'; did you mean 'killpg'? [-Werror=implicit-function-declaration]
  633 |                                 if (kill(pid, 0) == -1 && errno == ESRCH)
      |                                     ^~~~
      |                                     killpg

These build failures could be fixed by patching openrc but upstream
is not happy with this patch: https://github.com/OpenRC/openrc/pull/674.

So, as advised by Yann E. Morin, openrc is hidden away for uClibc, until
upstream has a proper fix.

Fixes:
 - http://autobuild.buildroot.org/results/494ef392a971ddb3c5c7b01e0149c6439018dbe7

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

system/Config.in

@@ -105,12 +105,13 @@ config BR2_INIT_OPENRC
 	bool "OpenRC"
 	depends on BR2_USE_MMU
 	depends on !BR2_STATIC_LIBS
+	depends on !BR2_TOOLCHAIN_BUILDROOT_UCLIBC
 	select BR2_PACKAGE_OPENRC
 	select BR2_PACKAGE_SKELETON_INIT_OPENRC if BR2_ROOTFS_SKELETON_DEFAULT
 
-comment "openrc needs a toolchain w/ dynamic library"
+comment "openrc needs a glibc or musl toolchain w/ dynamic library"
 	depends on BR2_USE_MMU
-	depends on BR2_STATIC_LIBS
+	depends on BR2_STATIC_LIBS && BR2_TOOLCHAIN_BUILDROOT_UCLIBC
 
 # In Buildroot, we decided not to support a split-usr when systemd is
 # used as an init system. This is a design decision, not a systemd