package/cpulimit: Disable build on OpenRISC with musl-libc

As reported in the following autobuild report:

http://autobuild.buildroot.net/results/2a9cf20949beac46d1c689df2c5b7ab0d59c08b5/

cpulimit does not build due to a lack of definition for elf_gregset_t
which is not currently provided in the or1k musl-libc port. While this
is being worked on, disable the build for or1k and musl-libc.

Reported-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Fixes: 9e8e80d1e335 ("package: Add cpulimit")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/cpulimit/Config.in

@@ -1,7 +1,12 @@
+comment "cpulimit needs a toolchain w/ threads, does not build open openrisc with musl"
+	depends on BR2_USE_MMU
+	depends on !BR2_TOOLCHAIN_HAS_THREADS || (BR2_or1k && BR2_TOOLCHAIN_USES_MUSL)
+
 config BR2_PACKAGE_CPULIMIT
 	bool "cpulimit"
 	depends on BR2_USE_MMU # fork()
 	depends on BR2_TOOLCHAIN_HAS_THREADS
+	depends on !(BR2_or1k && BR2_TOOLCHAIN_USES_MUSL)
 	help
 	  Cpulimit is a tool which limits the CPU usage of a process
 	  (expressed in percentage, not in CPU time)